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Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2019	Nov. 04, 2019
Class of Stock [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-38434
Entity Registrant Name	Dropbox, Inc.
Entity Central Index Key	0001467623
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-0138832
Entity Address, Address Line One	1800 Owens Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	857-6800
Title of 12(b) Security	Class A Common Stock, par value $0.00001 per share
Trading Symbol	DBX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Class A common stock
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		253,940,063
Class B common stock
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		161,382,933
Class C common stock
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		0

Condensed Consolidated Balance Sheets - USD ($)
$ in Millions

Sep. 30, 2019

Dec. 31, 2018

Current assets:

Cash and cash equivalents

$ 443.2

$ 519.3

Short-term investments

587.7

570.0

Trade and other receivables, net

38.4

28.6

Prepaid expenses and other current assets

64.3

92.3

Total current assets

1,133.6

1,210.2

Property and equipment, net

416.6

310.6

Operating lease right-of-use asset

581.7

Intangible assets, net

50.1

14.7

Goodwill

231.8

96.5

Other assets

72.8

62.1

Total assets

2,486.6

1,694.1

Current liabilities:

Accounts payable

31.3

33.3

Accrued and other current liabilities

149.9

164.5

Accrued compensation and benefits

79.1

80.9

Operating lease liability

76.0

Finance lease obligation

70.9

Finance lease obligation

73.8

Deferred revenue

541.1

485.0

Total current liabilities

948.3

837.5

Operating lease liability, non-current

626.2

Finance lease obligation, non-current

128.0

Finance lease obligation, non-current

89.9

Other non-current liabilities

^[1]

21.5

89.9

Total liabilities

1,724.0

1,017.3

Commitments and contingencies (Note 10)

Stockholders’ equity:

Additional paid-in capital

2,478.6

2,337.5

Accumulated deficit

(1,718.1)

(1,659.5)

Accumulated other comprehensive income (loss)

2.1

(1.2)

Total stockholders’ equity

762.6

676.8

Total liabilities and stockholders’ equity

$ 2,486.6

$ 1,694.1

[1]	As of December 31, 2018 the Company had non-current deferred rent of $81.0 million. As of September 30, 2019, deferred rent is now included in the determination of the Company's operating lease right-of-use asset due to the adoption of ASC 842.

Condensed Consolidated Balance Sheets (Parenthetical) $ in Millions	Dec. 31, 2018 USD ($)
Statement of Financial Position [Abstract]
Non-current deferred rent	$ 81.0

Condensed Consolidated Statements of Operations - USD ($)
shares in Millions, $ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2019

Sep. 30, 2018

Sep. 30, 2019

Sep. 30, 2018

Income Statement [Abstract]

Revenue

$ 428.2

$ 360.3

$ 1,215.3

$ 1,015.8

Cost of revenue

^[1],[2]

104.8

90.2

306.1

300.3

Gross profit

323.4

270.1

909.2

715.5

Operating expenses

Research and development

^[1],[2]

172.8

133.2

485.2

631.4

Sales and marketing

^[1],[2]

108.2

95.0

317.0

339.4

General and administrative

^[1],[2]

61.0

50.8

180.9

226.7

Total operating expenses

^[1],[2]

342.0

279.0

983.1

1,197.5

Loss from operations

(18.6)

(8.9)

(73.9)

(482.0)

Interest income, net

3.0

2.4

9.9

3.2

Other income, net

0.2

0.5

14.4

6.1

Loss before income taxes

(15.4)

(6.0)

(49.6)

(472.7)

Benefit from (provision for) income taxes

(1.6)

0.2

3.5

(2.7)

Net loss

$ (17.0)

$ (5.8)

$ (46.1)

$ (475.4)

Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)

$ (0.04)

$ (0.01)

$ (0.11)

$ (1.39)

Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)

414.4

403.9

412.4

342.0

[1]

During the nine months ended September 30, 2018, the Company recognized the cumulative unrecognized stock-based compensation of $418.7 million related to two-tier restricted stock units upon the effectiveness of the registration statement for the Company's IPO. See Note 1, "Description of the Business and Summary of Significant Accounting Policies" for further information.

[2]

Includes stock-based compensation as follows (in millions):



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018

Cost of revenue	$	4.1	$	3.2	$	11.8	$	43.9
Research and development	38.9		28.2		107.1		339.0
Sales and marketing	7.7		8.1		23.6		88.4
General and administrative	17.5		15.5		49.4		125.3

Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Cost of revenue
Allocated share-based compensation expense	$ 4.1	$ 3.2	$ 11.8	$ 43.9
Research and development
Allocated share-based compensation expense	38.9	28.2	107.1	339.0
Sales and marketing
Allocated share-based compensation expense	7.7	8.1	23.6	88.4
General and administrative
Allocated share-based compensation expense	$ 17.5	$ 15.5	$ 49.4	125.3
Two-Tier RSUs
Recognized cumulative unrecognized stock-based compensation				$ 418.7

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (17.0)	$ (5.8)	$ (46.1)	$ (475.4)
Other comprehensive income (loss), net of tax:
Change in foreign currency translation adjustments	0.0	0.0	1.6	(2.1)
Change in net unrealized gains (losses) on short-term investments	0.2	0.0	1.7	(0.2)
Total other comprehensive income (loss), net of tax	0.2	0.0	3.3	(2.3)
Comprehensive loss	$ (16.8)	$ (5.8)	$ (42.8)	$ (477.7)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Class A and Class B common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Convertible preferred stock
Shares outstanding, beginning of the period (in shares) at Dec. 31, 2017		196.8				147.6
Shareholders equity, beginning balance at Dec. 31, 2017	$ 102.9	$ 0.0	$ 533.1	$ (1,049.7)	$ 4.2	$ 615.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock units (in shares)		37.6
Shares repurchased for tax withholdings on release of restricted stock (in shares)		(14.5)
Shares repurchased for tax withholdings on release of restricted stock	(326.7)		(208.4)	(118.3)
Conversion of preferred stock to common stock in connection with initial public offering (in shares)		147.6				(147.6)
Conversion of preferred stock to common stock in connection with initial public offering			615.3			$ (615.3)
Issuance of common stock in connection with initial public offering and private placement, net of underwriters' discounts and commissions and issuance costs (in shares)		37.0
Issuance of common stock in connection with initial public offering and private placement, net of underwriters' discounts and commissions and issuance costs	739.7		739.7
Exercise of stock options and awards (in shares)		1.7
Exercise of stock options and awards	9.8		9.8
Stock-based compensation	595.5		595.5
Other comprehensive income	(2.3)				(2.3)
Net loss	(475.4)
Shares outstanding, end of the period (in shares) at Sep. 30, 2018		406.2				0.0
Shareholders equity, ending balance at Sep. 30, 2018	643.5	$ 0.0	2,285.0	(1,643.4)	1.9	$ 0.0
Shares outstanding, beginning of the period (in shares) at Jun. 30, 2018		402.3
Shareholders equity, beginning balance at Jun. 30, 2018	630.9	$ 0.0	2,248.4	(1,619.4)	1.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock units (in shares)		3.9
Shares repurchased for tax withholdings on release of restricted stock (in shares)		(1.5)
Shares repurchased for tax withholdings on release of restricted stock	(44.3)		(26.1)	(18.2)
Exercise of stock options and awards (in shares)		1.5
Exercise of stock options and awards	8.8		8.8
Stock-based compensation	53.9		53.9
Other comprehensive income	0.0
Net loss	(5.8)
Shares outstanding, end of the period (in shares) at Sep. 30, 2018		406.2				0.0
Shareholders equity, ending balance at Sep. 30, 2018	643.5	$ 0.0	2,285.0	(1,643.4)	1.9	$ 0.0
Shares outstanding, beginning of the period (in shares) at Dec. 31, 2018		409.6
Shareholders equity, beginning balance at Dec. 31, 2018	$ 676.8	$ 0.0	2,337.5	(1,659.5)	(1.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock units (in shares)		8.5
Shares repurchased for tax withholdings on release of restricted stock (in shares)	(3.1)	(3.1)
Shares repurchased for tax withholdings on release of restricted stock	$ (67.1)		(53.6)	(13.5)
Exercise of stock options and awards (in shares)	0.3	0.3
Exercise of stock options and awards	$ 2.0		2.0
Assumed stock options in connection with acquisition	0.8		0.8
Stock-based compensation	191.9		191.9
Other comprehensive income	3.3				3.3
Net loss	(46.1)
Shares outstanding, end of the period (in shares) at Sep. 30, 2019		415.3
Shareholders equity, ending balance at Sep. 30, 2019	762.6	$ 0.0	2,478.6	(1,718.1)	2.1
Shares outstanding, beginning of the period (in shares) at Jun. 30, 2019		413.4
Shareholders equity, beginning balance at Jun. 30, 2019	730.2	$ 0.0	2,428.4	(1,700.1)	1.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of restricted stock units (in shares)		3.0
Shares repurchased for tax withholdings on release of restricted stock (in shares)		(1.1)
Shares repurchased for tax withholdings on release of restricted stock	(19.0)		(18.0)	(1.0)
Stock-based compensation	68.2		68.2
Other comprehensive income	0.2				0.2
Net loss	(17.0)
Shares outstanding, end of the period (in shares) at Sep. 30, 2019		415.3
Shareholders equity, ending balance at Sep. 30, 2019	$ 762.6	$ 0.0	$ 2,478.6	$ (1,718.1)	$ 2.1

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flow from operating activities
Net loss	$ (46.1)	$ (475.4)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	132.5	121.6
Stock-based compensation	191.9	596.6
Net gains on equity investments	(5.7)	0.0
Amortization of deferred commissions	12.7	8.5
Other	(8.3)	(0.9)
Changes in operating assets and liabilities:
Trade and other receivables, net	(9.5)	0.4
Prepaid expenses and other current assets	(26.1)	(47.3)
Other assets	41.8	(10.4)
Accounts payable	(2.4)	(3.9)
Accrued and other current liabilities	9.5	40.6
Accrued compensation and benefits	(3.1)	7.2
Deferred revenue	54.7	60.8
Other non-current liabilities	(45.6)	3.9
Tenant improvement allowance reimbursement	45.4	0.0
Net cash provided by operating activities	341.7	301.7
Cash flow from investing activities
Capital expenditures	(110.6)	(27.6)
Business combinations, net of cash acquired	(171.6)	0.0
Purchases of short-term investments	(582.7)	(664.3)
Proceeds from sales of short-term investments	341.0	61.6
Proceeds from maturities of short-term investments	236.7	101.9
Other	8.4	(0.6)
Net cash used in investing activities	(278.8)	(529.0)
Cash flow from financing activities
Proceeds from initial public offering and private placement, net of underwriters' discounts and commissions	0.0	746.6
Payments of deferred offering costs	0.0	(4.5)
Shares repurchased for tax withholdings on release of restricted stock	(67.1)	(326.7)
Proceeds from issuance of common stock, net of repurchases	2.0	9.8
Principal payments on finance lease obligations	(71.8)
Principal payments on finance lease obligations		(84.1)
Other	(0.4)	(6.1)
Net cash (used in) provided by financing activities	(137.3)	335.0
Effect of exchange rate changes on cash and cash equivalents	(1.7)	(1.5)
Change in cash and cash equivalents	(76.1)	106.2
Cash and cash equivalents - beginning of period	519.3	430.0
Cash and cash equivalents - end of period	443.2	536.2
Supplemental cash flow data:
Property and equipment acquired under finance leases	$ 107.0
Property and equipment acquired under finance leases		$ 72.7

Description of the Business and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of the Business and Summary of Significant Accounting Policies

Business

Dropbox, Inc. (the “Company” or “Dropbox”) is a global collaboration platform. Dropbox was incorporated in May 2007 as Evenflow, Inc., a Delaware corporation, and changed its name to Dropbox, Inc. in October 2009. The Company is headquartered in San Francisco, California.

Basis of presentation and consolidation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the United States of America generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission ("SEC") regarding interim financial reporting. The accompanying unaudited condensed consolidated financial statements include the accounts of Dropbox and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

The condensed consolidated balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. The unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the balance sheets, statements of operations, statements of comprehensive loss, statements of stockholders' equity and the statements of cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full fiscal year ended December 31, 2019 or any future period.

The unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes thereto as of and for the year ended December 31, 2018, included in the Company's Annual Report on Form 10-K on file with the SEC ("Annual Report").

Initial public offering and private placement

On March 27, 2018, the Company closed its initial public offering ("IPO"), in which the Company issued and sold 26,822,409 shares of Class A common stock at $21.00 per share. The Company received aggregate proceeds of $538.2 million, net of underwriters' discounts and commissions, before deducting offering costs of $6.9 million, net of reimbursements.

Immediately prior to the closing of the Company’s IPO, 147,310,563 shares of convertible preferred stock outstanding converted into an equivalent number of shares of Class B common stock. Further, pursuant to transfer agreements with certain of the Company’s stockholders, 258,620 shares of the Company’s convertible preferred stock and 2,609,951 shares of the Company’s Class B common stock automatically converted into an equivalent number of shares of Class A common stock.

Immediately subsequent to the closing of the Company's IPO, Salesforce Ventures LLC purchased 4,761,905 shares of Class A common stock from the Company at $21.00 per share. The Company received aggregate proceeds of $100.0 million and did not pay any underwriting discounts or commissions with respect to the shares that were sold in the private placement.

On March 28, 2018, the underwriters exercised their option to purchase an additional 5,400,000 shares of the Company's Class A common stock at $21.00 per share. This transaction closed on April 3, 2018, resulting in additional proceeds of $108.4 million, net of underwriters' discounts and commissions.

The Company’s net proceeds from the IPO, the concurrent private placement, and underwriters' option totaled $746.6 million, before deducting offering costs of $6.9 million, net of reimbursements.

Upon the effectiveness of the registration statement for the Company's IPO, which was March 22, 2018, the liquidity event-related performance vesting condition, referred to as the Performance Vesting Condition, associated with the Company's two-tier restricted stock units ("RSUs") was satisfied. As a result, the Company recognized the cumulative unrecognized stock-based compensation related to its two-tier RSUs using the accelerated attribution method of $418.7 million attributable to service prior to such effective date.

During the first quarter of 2018, the Company's Board of Directors approved the acceleration of the Performance Vesting Condition for which the service condition was satisfied, to occur upon the effectiveness of the registration statement for the Company's IPO, rather than six months following an IPO. As a result, the Company released 26.8 million shares of common stock underlying the two-tier RSUs for which the Performance Vesting Condition was satisfied and recorded $13.9 million in employer related payroll tax expenses associated with these same awards.

Stock split

On March 7, 2018, the Company effected a 1-for-1.5 reverse stock split of its capital stock. All of the share and per share information referenced throughout the condensed consolidated financial statements and notes to the condensed consolidated financial statements have been retroactively adjusted to reflect this reverse stock split.

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the Company’s condensed consolidated financial statements and accompanying notes. These estimates are based on information available as of the date of the condensed consolidated financial statements. Management evaluates these estimates and assumptions on a regular basis. Actual results may differ materially from these estimates.

The Company’s most significant estimates and judgments involve the estimation of the fair value of market-based awards and the valuation of acquired intangible assets and goodwill from business combinations.

Financial information about segments and geographic areas

The Company manages its operations and allocates resources as a single operating segment. Further, the Company manages, monitors, and reports its financials as a single reporting segment. The Company’s chief operating decision-maker is its Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of making operating decisions, assessing financial performance, and allocating resources. See Note 16, "Geographic Areas" for information regarding the Company’s long-lived assets and revenue by geography.

Foreign currency transactions

The assets and liabilities of the Company’s foreign subsidiaries are translated from their respective functional currencies into U.S. dollars at the exchange rates in effect at the balance sheet date. Revenue and expense amounts are translated at the average exchange rate for the period. Foreign currency translation gains and losses are recorded in other comprehensive income (loss).

Gains and losses realized from foreign currency transactions (those transactions denominated in currencies other than the foreign subsidiaries’ functional currency) are included in other income, net. Monetary assets and liabilities are remeasured using foreign currency exchange rates at the end of the period, and non-monetary assets are remeasured based on historical exchange rates. The Company recorded net foreign currency transaction losses of $0.6 million and $1.1 million during the three and nine months ended September 30, 2019, respectively, and net foreign currency transaction losses of $1.0 million and $1.4 million during the three and nine months ended September 30, 2018, respectively.

Revenue recognition

The Company derives its revenue from subscription fees from customers for access to its platform. The Company’s policy is to exclude sales and other indirect taxes when measuring the transaction price of its subscription agreements. The Company accounts for revenue contracts with customers through the following steps:


•	Identification of the contract, or contracts, with a customer


•	Identification of the performance obligations in the contract


•	Determination of the transaction price


•	Allocation of the transaction price to the performance obligations in the contract


•	Recognition of revenue when, or as, the Company satisfies a performance obligation

The Company’s subscription agreements generally have monthly or annual contractual terms and a small percentage have multi-year contractual terms. Revenue is recognized ratably over the related contractual term beginning on the date that the platform is made available to a customer. Access to the platform represents a series of distinct services as the Company continually provides access to, and fulfills its obligation to the end customer over the subscription term. The series of distinct services represents a single performance obligation that is satisfied over time. The Company recognizes revenue ratably because the customer receives and consumes the benefits of the platform throughout the contract period. The Company’s contracts are generally non-cancelable.

The Company bills in advance for monthly contracts and typically bills annually in advance for contracts with terms of one year or longer. The Company also recognizes an immaterial amount of contract assets, or unbilled receivables, primarily relating to consideration for services completed but not billed at the reporting date. Unbilled receivables are classified as receivables when the Company has the right to invoice the customer.

The Company records contract liabilities when cash payments are received or due in advance of performance to deferred revenue. Deferred revenue primarily relates to the advance consideration received from the customer.

The price of subscriptions is generally fixed at contract inception and therefore, the Company’s contracts do not contain a significant amount of variable consideration. As a result, the amount of revenue recognized in the periods presented from performance obligations satisfied (or partially satisfied) in previous periods was not material.

The Company recognized $241.3 million and $452.9 million of revenue during the three and nine months ended September 30, 2019, respectively, and recognized $213.2 million and $390.1 million of revenue during the three and nine months ended September 30, 2018, respectively, that was included in the deferred revenue balances at the beginning of their respective periods.

As of September 30, 2019, future estimated revenue related to performance obligations that were unsatisfied or partially unsatisfied was $588.7 million. The substantial majority of the unsatisfied performance obligations will be satisfied over the next twelve months.

Stock-based compensation

The Company has granted RSUs to its employees and members of the Board of Directors under the 2008 Equity Incentive Plan (“2008 Plan”), the 2017 Equity Incentive Plan (“2017 Plan”), and the 2018 Equity Incentive Plan ("2018 Plan" and together with the 2008 Plan and 2017 Plan, the "Dropbox Equity Incentive Plans"). The Company has granted the following types of RSUs under the Dropbox Equity Incentives Plans:

•

One-tier RSUs, which have a service-based vesting condition over a four-year period. These awards typically have a cliff vesting period of one year and continue to vest quarterly thereafter. The Company began granting one-tier RSUs under its 2008 Plan in August 2015, and it continues to grant one-tier RSUs under its 2018 Plan. The Company recognizes compensation expense associated with one-tier RSUs ratably on a straight-line basis over the requisite service period and accounts for forfeitures in the period in which they occur.

•

Two-tier RSUs, which had both a service-based vesting condition and a Performance Vesting Condition. The Performance Vesting Condition was satisfied on the effectiveness of the registration statement related to the Company's IPO. Prior to August 2015, the Company granted two-tier RSUs under the 2008 Plan. The last grant date for two-tier RSUs was in May 2015. The Company recognized compensation expense associated with two-tier RSUs using the accelerated attribution method over the requisite service period.

As of September 30, 2019, the Company only had one-tier RSUs outstanding under the Dropbox Equity Incentive Plans.

Since August 2015, the Company has granted one-tier RSUs as the only stock-based payment awards to its employees, with the exception of awards granted to its co-founders, and has not granted any stock options to employees since then. The fair values of the common stock underlying the RSUs granted in periods prior to the date of the Company's IPO were determined by the Board of Directors, with input from management and contemporaneous third-party valuations, which were performed at least quarterly. For valuations after the Company's IPO, the Board of Directors determines the fair value of each share of

underlying common stock based on the closing price of the Company's Class A common stock as reported on the Nasdaq Global Select Market on the date of the grant.

In connection with the acquisition of JN Projects, Inc. (d/b/a HelloSign) ("HelloSign"), the Company assumed unvested stock options that had been granted under the HelloSign's 2011 Equity Incentive Plan. The fair value of options assumed were based upon the Black-Scholes option-pricing model, see Note 12, "Stockholders' Equity" for further information.

In December 2017, the Board of Directors approved a grant to the Company’s co-founders of restricted stock awards (“RSAs”) with respect to 14.7 million shares of Class A Common Stock in the aggregate (collectively, the “Co-Founder Grants”), of which 10.3 million RSAs were granted to Mr. Houston, the Company’s co-founder and Chief Executive Officer, and 4.4 million RSAs were granted to Mr. Ferdowsi, the Company’s co-founder and Director. These Co-Founder Grants have service-based, market-based, and performance-based vesting conditions. The Company estimated the grant date fair value of the Co-Founder Grants using a model based on multiple stock price paths developed through the use of a Monte Carlo simulation that incorporates into the valuation the possibility that the Stock Price Targets may not be satisfied. See Note 12, "Stockholders' Equity" for further information.

Cash and cash equivalents

Cash consists primarily of cash on deposit with banks and includes amounts in transit from payment processors for credit and debit card transactions, which typically settle within five business days. Cash equivalents include highly liquid investments purchased with an original maturity date of 90 days or less from the date of purchase.

Short-term investments

The Company’s short-term investments are primarily comprised of corporate notes and obligations, U.S. Treasury securities, certificates of deposit, asset-backed securities, commercial paper, U.S. agency obligations and municipal securities. The Company determines the appropriate classification of its short-term investments at the time of purchase and reevaluates such designation at each balance sheet date. The Company has classified and accounted for its short-term investments as available-for-sale securities as the Company may sell these securities at any time for use in its current operations or for other purposes, even prior to maturity. As a result, the Company classifies its short-term investments, including securities with stated maturities beyond twelve months, within current assets in the condensed consolidated balance sheets.

The Company's short-term investments are classified as available-for-sale securities and are recorded at fair value each reporting period. Unrealized gains and losses on these short-term investments are reported as a separate component of accumulated other comprehensive income (loss) in the condensed consolidated balance sheets until realized. Interest income is reported within interest income, net in the condensed consolidated statements of operations. The Company periodically evaluates its short-term investments to assess whether those with unrealized loss positions are other-than-temporarily impaired. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time the investment has been in a loss position, the extent to which the fair value is less than the Company’s cost basis, and the financial condition and near-term prospects of the investee. Realized gains and losses are determined based on the specific identification method and are reported in other income, net in the condensed consolidated statements of operations. If the Company determines that the decline in an investment’s fair value is other-than-temporary, the difference is recognized as an impairment loss in the condensed consolidated statements of operations.

Concentrations of credit risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, accounts receivable, and short-term investments. The Company places its cash and cash equivalents and short-term investments with well-established financial institutions.

Trade accounts receivables are typically unsecured and are derived from revenue earned from customers located around the world. Two customers accounted for 12% and 45% of total trade and other receivables, net as of September 30, 2019. Two customers accounted for 14% and 23% of total trade and other receivables, net as of December 31, 2018. No customer accounted for more than 10% of the Company’s revenue in the periods presented.

Non-trade receivables

The Company records non-trade receivables to reflect amounts due for activities outside of its subscription agreements, such as receivables resulting from tenant improvement allowances prior to the adoption of ASC 842. Non-trade receivables totaled $14.0 million and $46.2 million, as of September 30, 2019 and December 31, 2018, respectively, and are classified within prepaid expenses and other current assets and other assets in the accompanying condensed consolidated balance sheets. See "—Lease obligations” for further discussion.

Deferred commissions, net

Deferred commissions, net is stated as gross deferred commissions less accumulated amortization. Sales commissions earned by the Company’s sales force and third-party resellers, as well as related payroll taxes, are considered to be incremental and recoverable costs of obtaining a contract with a customer. These amounts have been capitalized as deferred commissions within prepaid and other current assets and other assets on the condensed consolidated balance sheets. The Company deferred incremental costs of obtaining a contract of $7.4 million and $21.1 million during the three and nine months ended September 30, 2019, respectively, and $7.4 million and $24.9 million during the three and nine months ended September 30, 2018, respectively.

Deferred commissions, net included in prepaid and other current assets were $18.7 million and $14.5 million as of September 30, 2019 and December 31, 2018, respectively. Deferred commissions, net included in other assets were $42.5 million and $38.3 million as of September 30, 2019 and December 31, 2018, respectively.

Deferred commissions are typically amortized over a period of benefit of five years. The period of benefit was estimated by considering factors such as historical customer attrition rates, the useful life of the Company’s technology, and the impact of competition in its industry. Amortized costs were $4.6 million and $12.7 million for the three and nine months ended September 30, 2019, respectively, and $3.2 million and $8.5 million for the three and nine months ended September 30, 2018, respectively. Amortized costs are included in sales and marketing expense in the accompanying condensed consolidated statements of operations. There was no impairment loss in relation to the deferred costs for any period presented.

Property and equipment, net

Equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful life of the related asset, which is generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the related lease.

The following table presents the estimated useful lives of property and equipment:



Property and equipment		Useful life

Datacenter and other computer equipment		3 to 5 years
Office equipment and other		3 to 7 years
Leasehold improvements		Lesser of estimated useful life or remaining lease term

Equity investments

The Company holds an equity investment in a publicly traded company in which the Company does not have a controlling interest or significant influence. The investment is measured using quoted prices in its active market with changes recorded in other income, net, in the condensed consolidated statement of operations. As of September 30, 2019, the Company's equity investment totaled $10.7 million and is included in other assets in the condensed consolidated balance sheet. The Company recognized net losses of $1.7 million and net gains of $5.7 million related to changes in quoted prices in the investment’s active market during the three and nine months ended September 30, 2019, respectively. The investment is classified as a level 1 investment within the fair value hierarchy.

Lease obligations

The Company leases office space, datacenters, and equipment under non-cancelable finance and operating leases with various expiration dates through 2033. The Company determines if an arrangement contains a lease at inception.

Operating lease right-of-use assets and lease liabilities are recognized at the present value of the future lease payments at commencement date. The interest rate implicit in the Company’s operating leases is not readily determinable, and therefore an incremental borrowing rate is estimated to determine the present value of future payments. The estimated incremental borrowing rate factors in a hypothetical interest rate on a collateralized basis with similar terms, payments, and economic environments. Operating lease right-of-use assets also include any prepaid lease payments and lease incentives.

Certain of the operating lease agreements contain rent concession, rent escalation, and option to renew provisions. Rent concession and rent escalation provisions are considered in determining the single lease cost to be recorded over the lease term. Single lease cost is recognized on a straight-line basis over the lease term commencing on the date the Company has the right to use the leased property. The lease terms may include options to extend or terminate the lease. The Company generally uses the base, non-cancelable, lease term when recognizing the lease assets and liabilities, unless it is reasonably certain that the option will be exercised.

In addition, certain of the Company’s operating lease agreements contain tenant improvement allowances from its landlords. These allowances are accounted for as lease incentives and decrease the Company's right-of-use asset and reduce single lease cost over the lease term.

The Company leases certain equipment from various third parties, through equipment finance leases. These leases either include a bargain purchase option, a full transfer of ownership at the completion of the lease term, or the terms of the leases are at least 75 percent of the useful lives of the assets and are therefore classified as finance leases. These leases are capitalized in property and equipment and the related amortization of assets under finance leases is included in depreciation and amortization expense in the Company’s condensed consolidated statements of operations. Initial asset values and finance lease obligations are based on the present value of future minimum lease payments.

The Company’s finance lease agreements may contain lease and non-lease components. The non-lease components include payments for support on infrastructure equipment obtained via finance leases, which when not significant in relation to the overall agreement, are combined with the lease components and accounted for together as a single lease component.

Business combinations

The Company uses best estimates and assumptions, including but not limited to, future expected cash flows, expected asset lives, and discount rates, to assign a fair value to the tangible and intangible assets acquired and liabilities assumed in business combinations as of the acquisition date. These estimates are inherently uncertain and subject to refinement. During the measurement period, which may be up to one year from the acquisition date, adjustments to the fair value of these tangible and intangible assets acquired and liabilities assumed may be recorded, with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the fair value of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the Company’s condensed consolidated statements of operations.

Long-lived assets, including goodwill and other acquired intangible assets, net

The Company evaluates the recoverability of its property and equipment and finite-lived intangible assets for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. The evaluation is performed at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability of these assets is measured by a comparison of the carrying amounts to the future undiscounted cash flows the assets are expected to generate. If such review determines that the carrying amount of specific property and equipment or intangible assets is not recoverable, the carrying amount of such assets is reduced to its fair value.

The Company reviews goodwill for impairment at least annually in the fourth quarter, or more frequently if events or changes in circumstances would more likely than not reduce the fair value of its single reporting unit below its carrying value.

The Company has not recorded impairment charges on property and equipment, goodwill, or intangible assets for the periods presented in these condensed consolidated financial statements.

Acquired property and equipment and finite-lived intangible assets are amortized over their useful lives. The Company evaluates the estimated remaining useful life of these assets when events or changes in circumstances warrant a revision to the

remaining period of amortization. If the Company revises the estimated useful life assumption for any asset, the remaining unamortized balance is amortized or depreciated over the revised estimated useful life on a prospective basis.

Income taxes

Deferred income tax balances reflect the effects of temporary differences between the financial reporting and tax bases of the Company’s assets and liabilities using enacted tax rates expected to apply when taxes are actually paid or recovered. In addition, deferred tax assets are recorded for net operating loss and credit carryforwards.

A valuation allowance is provided against deferred tax assets unless it is more likely than not that they will be realized based on all available positive and negative evidence. Such evidence includes, but is not limited to, recent cumulative earnings or losses, expectations of future taxable income by taxing jurisdiction, and the carry-forward periods available for the utilization of deferred tax assets.

The Company uses a two-step approach to recognizing and measuring uncertain income tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates it is more likely than not that the position will be sustained on audit. The second step is to measure the tax benefit as the largest amount which is more than 50% likely of being realized upon ultimate settlement. The Company recognizes interest and penalties related to unrecognized tax benefits as income tax expense.

Although the Company believes that it has adequately reserved for its uncertain tax positions, it can provide no assurance that the final tax outcome of these matters will not be materially different. The Company evaluates its uncertain tax positions on a regular basis and evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, such as the 2017 Tax Cuts and Jobs Act ("2017 Tax Reform Act"), correspondence with tax authorities during the course of an audit, and effective settlement of audit issues.

To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on the Company’s financial condition and results of operations.

Fair value measurement

The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value measurements for assets and liabilities, the Company considers the principal or most advantageous market in which it would transact and the market-based risk measurements or assumptions that market participants would use in pricing the asset or liability, such as risks inherent in valuation techniques, transfer restrictions, and credit risk. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1—Quoted prices in active markets for identical assets or liabilities.

Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

Recently issued accounting pronouncements not yet adopted

In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be

recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes will result in more timely recognition of credit losses. The guidance is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The Company does not expect the adoption of ASU No. 2016-13 to have a significant impact on its consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820), which amends disclosure requirements for fair value measurements by requiring new disclosures, modifying existing requirements, and eliminating others. The amendments are the result of a broader disclosure project, which aims to improve the effectiveness of disclosures. ASU No. 2018-13 is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company does not expect the adoption of ASU No. 2018-13 to have a significant impact on its disclosures.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40), Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. Under existing U.S. GAAP, there is diversity in practice in accounting for the costs of implementing cloud computing arrangements that are service contracts. The amendments in ASU No. 2018-15 amend the definition of a hosting arrangement and requires a customer in a hosting arrangement that is a service contract to capitalize certain costs as if the arrangement were an internal-use software project. The guidance is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company is currently evaluating the impact of adopting ASU No. 2018-15.

Recently adopted accounting pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). Most prominent among the changes in the standard is the recognition of right-of-use assets (“ROU assets”) and lease liabilities by lessees for certain leases classified as operating leases under current GAAP. The Company has made the policy election to not recognize a lease liability or right-of-use asset for short-term operating leases.

The Company adopted the standard as of January 1, 2019, using the modified retrospective approach and has elected to use the optional transition method which allows the Company to apply the guidance of ASC 840, including disclosure requirements, in the comparative periods presented. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard, which among other things, allowed the Company to carry forward the historical lease classification related to agreements entered prior to adoption.

The most significant impact was the recognition of ROU assets and lease liabilities for operating leases. The adoption of the new standard resulted in the recording of operating ROU assets and lease liabilities of approximately $431.7 million and $502.4 million, respectively, as of January 1, 2019.

The accounting for finance leases remained unchanged, except for the accounting for certain non-lease components. Lease and non-lease components will be accounted for as a single lease component if the non-lease component is determined to be insignificant to the total agreement.

The cumulative impact of transition to retained earnings, recorded as of the adoption date, was not material. The standard did not materially impact consolidated net earnings and had no impact on cash flows.

In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. Under existing U.S. GAAP, the effects of changes in tax rates and laws on deferred tax balances are recorded as a component of income tax expense in the period in which the law was enacted. When deferred tax balances related to items originally recorded in accumulated other comprehensive income are adjusted, certain tax effects become stranded in accumulated other comprehensive income. The amendments in ASU No. 2018-02 allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the 2017 Tax Reform Act. The amendments in ASU No. 2018-02 also require certain disclosures about stranded tax effects. The Company adopted ASU No. 2018-02 on January 1, 2019. The adoption of the standard did not have a material impact on the Company's condensed consolidated financial statements.

In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting. Under existing U.S. GAAP, the measurement date for equity awards granted to nonemployees is the earlier of the performance commitment date or the date the performance is complete. The amendments in ASU No. 2018-07 allow for measurement of

these awards on the grant date, consistent with equity awards granted to employees. The Company adopted ASU No. 2018-07 on January 1, 2019. The adoption of the standard did not have a material impact on the Company's condensed consolidated financial statements.

Cash, Cash Equivalents and Short-Term Investments

9 Months Ended

Sep. 30, 2019

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents and Short-Term Investments

The amortized cost, unrealized gains and losses and estimated fair value of the Company's cash, cash equivalents and short-term investments as of September 30, 2019 and December 31, 2018 consisted of the following:



	As of September 30, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value

Cash	$	102.0	$	—	$	—		$	102.0
Cash equivalents:
Money market funds	333.2		—		—			333.2
U.S. Treasury securities	7.0		—		—			7.0
Asset-backed securities	1.0		—		—			1.0
Total cash and cash equivalents	$	443.2	$	—	$	—		$	443.2
Short-term investments
Corporate notes and obligations	258.5		1.4		—			259.9
U.S. Treasury securities	176.1		0.3		(0.1		)	176.3
Certificates of deposit	44.9		—		—			44.9
Asset-backed securities	44.8		—		(0.1		)	44.7
Commercial Paper	34.4		—		—			34.4
U.S. agency obligations	25.1		—		—			25.1
Municipal securities	2.4		—		—			2.4
Total short-term investments	586.2		1.7		(0.2		)	587.7
Total	$	1,029.4	$	1.7	$	(0.2	)	$	1,030.9



	As of December 31, 2018
	Amortized cost		Unrealized gain		Unrealized loss			Estimated fair value

Cash	$	103.0	$	—	$	—		$	103.0
Cash equivalents
Money market funds	355.5		—		—			355.5
U.S. Treasury securities	33.4		—		—			$	33.4
Commercial paper	27.4		—		—			27.4
Total cash and cash equivalents	$	519.3	$	—	$	—		$	519.3
Short-term investments
Corporate notes and obligations	269.6		0.1		(0.5		)	269.2
U.S. Treasury securities	176.0		—		(0.1		)	175.9
Certificates of deposit	70.6		—		—			70.6
U.S. agency obligations	37.1		—		—			37.1
Commercial paper	17.2		—		—			17.2
Total short-term investments	570.5		0.1		(0.6		)	570.0
Total	$	1,089.8	$	0.1	$	(0.6	)	$	1,089.3

Included in cash and cash equivalents is cash in transit from payment processors for credit and debit card transactions of $16.6 million and $11.9 million as of September 30, 2019 and December 31, 2018, respectively.

All short-term investments were designated as available-for-sale securities as of September 30, 2019 and December 31, 2018.

The following table presents the contractual maturities of the Company’s short-term investments as of September 30, 2019:



	As of September 30, 2019
	Amortized cost		Estimated fair value

Due within one year	$	261.5	$	261.9
Due between one to three years	324.7		325.8
Total	$	586.2	$	587.7

The Company had 65 short-term investments in unrealized loss positions as of September 30, 2019. There were no material unrealized losses from available-for-sale securities and no material realized gains or losses from available-for-sale securities that were reclassified out of accumulated other comprehensive income (loss) for the three and nine months ended September 30, 2019 and 2018.

For investments in available-for-sale debt securities that have unrealized losses, the Company evaluates whether (i) it has the intention to sell any of these investments and (ii) whether it is not more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. Based on this evaluation, the Company determined that there were no other-than-temporary impairments associated with short-term investments as of September 30, 2019.

The Company recorded interest income from its cash, cash equivalents, and short-term investments of $5.7 million and $17.5 million during the three and nine months ended September 30, 2019, respectively, and $5.0 million and $10.8 during the three and nine months ended September 30, 2018, respectively.

Fair Value Measurements

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company measures its financial instruments at fair value each reporting period using a fair value hierarchy that prioritizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. A financial instrument’s classification within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis using the input categories discussed in Note 1:



	As of September 30, 2019
	Level 1		Level 2		Level 3		Total

Cash equivalents
Money market funds	$	333.2	$	—	$	—	$	333.2
U.S. Treasury securities	—		7.0		—		7.0
Asset-backed securities	—		1.0		—		1.0
Total cash equivalents	$	333.2	$	8.0	$	—	$	341.2
Short-term investments
Corporate notes and obligations	—		259.9		—		259.9
U.S. Treasury securities	—		176.3		—		176.3
Certificates of deposit	—		44.9		—		44.9
Asset-backed securities	—		44.7		—		44.7
Commercial paper	—		34.4		—		34.4
U.S. agency obligations	—		25.1		—		25.1
Municipal securities	—		2.4		—		2.4
Total short-term investments	—		587.7		—		587.7
Equity investments	10.7		—		—		10.7
Total	$	343.9	$	595.7	$	—	$	939.6



	As of December 31, 2018
	Level 1		Level 2		Level 3		Total

Cash equivalents
Money market funds	$	355.5	$	—	$	—	$	355.5
U.S. Treasury securities	—		33.4		—		33.4
Commercial paper	—		27.4		—		27.4
Total cash equivalents	$	355.5	$	60.8	—		$	416.3
Short-term investments
Corporate notes and obligations	—		269.2		—		269.2
U.S. Treasury securities	—		175.9		—		175.9
Certificates of deposit	—		70.6		—		70.6
U.S agency obligations	—		37.1		—		37.1
Commercial paper	—		17.2		—		17.2
Total short-term investments	—		570.0		—		570.0
Total	$	355.5	$	630.8	$	—	$	986.3

The Company had no transfers between levels of the fair value hierarchy.

The carrying amounts of certain financial instruments, including cash held in banks, accounts receivable and accounts payable approximate fair value due to their short-term maturities and are excluded from the fair value table above.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Property and Equipment, Net

9 Months Ended

Sep. 30, 2019

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following:



	As of
	September 30, 2019			December 31, 2018

Datacenter and other computer equipment	$	741.9		$	667.4
Furniture and fixtures	34.6			23.8
Leasehold improvements	203.6			150.5
Construction in process	19.7			32.8
Total property and equipment	999.8			874.5
Accumulated depreciation and amortization	(583.2		)	(563.9		)
Property and equipment, net	$	416.6		$	310.6

The Company leases certain infrastructure from various third parties, through equipment finance leases. Infrastructure assets as of September 30, 2019 and December 31, 2018, respectively included a total of $299.1 million and $362.8 million acquired under finance lease agreements. These leases are capitalized in property and equipment, and the related amortization of assets under finance leases is included in depreciation and amortization expense. The accumulated depreciation of the infrastructure under finance leases totaled $117.6 million and $211.7 million as of September 30, 2019 and December 31, 2018, respectively.

Construction in process includes costs primarily related to construction of leasehold improvements for office buildings and datacenters.

In the third quarter of 2019, the Company relocated from its former corporate headquarters to its new corporate headquarters. During the third quarter, the Company completed recognizing depreciation expense on assets related to its former headquarters, and commenced depreciation expense related to assets for its new corporate headquarters.

Depreciation expense related to property and equipment was $37.1 million and $122.5 million for the three and nine months ended September 30, 2019, respectively, and $43.3 million and $115.4 million for the three and nine months ended September 30, 2018, respectively.

Business Combinations

9 Months Ended

Sep. 30, 2019

Business Combinations [Abstract]

Business Combinations

On February 8, 2019, the Company acquired all outstanding stock of JN Projects, Inc. (d/b/a HelloSign) ("HelloSign"), which provides an e-signature and document workflow platform. The acquisition of HelloSign expands the Company's content collaboration capabilities to include additional business-critical workflows. The results of HelloSign operations have been included in the Company’s consolidated results of operations since the date of acquisition.

The purchase consideration transferred consisted of the following:



	Purchase consideration
Cash paid to common and preferred stockholders and vested option holders	$	175.2
Transaction costs paid by Dropbox on behalf of HelloSign	2.4
Fair value of assumed HelloSign options attributable to pre-combination services ⁽¹⁾	0.8
Purchase price adjustments	(0.5		)
Total purchase consideration	$	177.9

⁽¹⁾The fair value of options assumed were based upon the Black-Scholes option-pricing model.

In addition to the total purchase consideration above, the Company has compensation agreements with key HelloSign personnel consisting of $48.5 million in future cash payments subject to on-going employee service. The related expense will be recognized within research and development expenses over the required service period of three years, and the payments will begin in the first quarter of 2020 if the requisite service is provided.

The purchase consideration was preliminarily allocated to the tangible and intangible assets and liabilities acquired as of the acquisition date, with the excess recorded to goodwill as shown below. The fair value of assets and liabilities acquired may change as additional information is received during the measurement period. The measurement period will end no later than one-year from the acquisition date.



Assets acquired:
Cash and cash equivalents	$	5.5
Short-term investments	7.8
Acquisition-related intangible assets	44.6
Accounts receivable, prepaid and other assets	5.0
Total assets acquired	$	62.9

Liabilities assumed:
Accounts payable, accrued and other liabilities	$	6.3
Deferred revenue	4.8
Deferred tax liability	6.9
Total liabilities assumed	18.0
Net assets acquired, excluding goodwill	44.9
Total purchase consideration	177.9
Estimated goodwill ⁽²⁾	$	133.0

⁽²⁾ The goodwill recognized was primarily attributable to the opportunity to expand the user base of the Company's platform. The goodwill is not deductible for U.S. federal income tax purposes.

The fair value of the separately identifiable finite-lived intangible assets acquired and estimated weighted average useful lives are as follows:



	Estimated fair values		Estimated weighted average useful lives (In years)
Customer relationships	$	20.5	4.9
Developed technology	19.6		5.0
Trade name	4.5		5.0
Total acquisition-related intangible assets	$	44.6

The fair values of the acquisition-related intangibles were determined using the following methodologies: the multi-period excess earnings method, replacement cost method, and the relief from royalty method, for customer relationships, developed technology, and the trade name, respectively. The valuation model inputs required the application of significant judgment by management. The acquired intangible assets have a total weighted average amortization period of 4.9 years.

One-time acquisition-related diligence costs of $1.0 million were expensed within general and administrative expenses as incurred during the nine months ended September 30, 2019.

Intangible Assets

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

Intangible assets consisted of the following:



	As of September 30,			As of December 31,			Weighted- average remaining useful life (In years)
	2019			2018			Weighted- average remaining useful life (In years)
Developed technology	$	25.0		$	47.0		4.4
Customer relationships	20.5			—			4.3
Software	20.0			19.2			1.8
Patents	13.0			13.0			7.7
Assembled workforce in asset acquisitions	12.6			12.6			1.3
Licenses	4.6			4.6			1.8
Trademarks and trade names	5.2			0.7			4.4
Other	3.3			3.3			5.8
Total intangibles	104.2			100.4
Accumulated amortization	(54.1		)	(85.7		)
Intangible assets, net	$	50.1		$	14.7

During the first quarter of 2019 the Company retired $41.7 million in fully amortized developed technology assets.

Amortization expense was $3.6 million and $10.1 million for the three and nine months ended September 30, 2019, respectively, and $1.5 million and $4.7 million for the three and nine months ended September 30, 2018, respectively.

Expected future amortization expense for intangible assets as of September 30, 2019, is as follows:




Remaining three months of Fiscal 2019	$	3.6
2020	13.6
2021	11.3
2022	8.0
2023	7.7
Thereafter	5.9
Total	$	50.1

Goodwill

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

Goodwill represents the excess of the purchase price in a business combination over the fair value of net tangible and intangible assets acquired. The changes in the carrying amounts of goodwill were as follows:



Balance at December 31, 2018	$	96.5
HelloSign acquisition	133.0
Effect of foreign currency translation	2.3
Balance at September 30, 2019	$	231.8

The goodwill acquired from HelloSign is carried in U.S. dollars, while goodwill from previous acquisitions is denominated in other foreign currencies.

Goodwill amounts are not amortized, but tested for impairment on an annual basis. There was no impairment of goodwill as of September 30, 2019 and December 31, 2018.

Revolving Credit Facility	9 Months Ended
Revolving Credit Facility	Sep. 30, 2019
Debt Disclosure [Abstract]
Revolving Credit Facility	Revolving Credit Facility In April 2017, the Company entered into an amended and restated credit and guaranty agreement which provided for a $600.0 million revolving loan facility (the “revolving credit facility”). In conjunction with the revolving credit facility, the Company paid upfront issuance fees of $2.6 million, which are being amortized over the five-year term of the agreement. In February 2018, the Company amended its revolving credit facility to, among other things, permit the Company to make certain investments, enter into an unsecured standby letter of credit facility and increase its standby letter of credit sublimit to $187.5 million. The Company increased its borrowing capacity under the revolving credit facility from $600.0 million to $725.0 million. The Company may from time to time request increases in its borrowing capacity under the revolving credit facility of up to $275.0 million, provided no event of default has occurred or is continuing or would result from such increase. In conjunction with the amendment, the Company paid upfront issuance fees of $0.4 million, which are being amortized over the remaining term of the agreement. Pursuant to the terms of the revolving credit facility, the Company may issue letters of credit under the revolving credit facility, which reduce the total amount available for borrowing. Pursuant to the terms of the revolving credit facility, the Company is required to pay an annual commitment fee that accrues at a rate of 0.20% per annum on the unused portion of the borrowing commitments under the revolving credit facility. In addition, the Company is required to pay a fee in connection with letters of credit issued under the revolving credit facility, which accrues at a rate of 1.5% per annum on the amount of such letters of credit outstanding. There is an additional fronting fee of 0.125% per annum multiplied by the average aggregate daily maximum amount available under all letters of credit. Borrowings under the revolving credit facility bear interest, at the Company’s option, at an annual rate based on LIBOR plus a spread of 1.50% or at an alternative base rate plus a spread of 0.50%. The revolving credit facility contains customary conditions to borrowing, events of default and covenants, including covenants that restrict the Company’s ability to incur indebtedness, grant liens, make distributions to holders of the Company or its subsidiaries’ equity interests, make investments, or engage in transactions with its affiliates. In addition, the revolving credit facility contains financial covenants, including a consolidated leverage ratio covenant and a minimum liquidity balance of $100.0 million, which includes any available borrowing capacity. The Company was in compliance with the covenants of the revolving credit facility as of September 30, 2019 and December 31, 2018, respectively. The Company had an aggregate of $60.0 million of letters of credit outstanding under the revolving credit facility as of September 30, 2019, and the Company’s total available borrowing capacity under the revolving credit facility was $665.0 million as of September 30, 2019. The Company’s letters of credit expire between October 2019 and April of 2022.

Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Leases

The Company has operating leases for corporate offices and datacenters, and finance leases for infrastructure equipment. The Company’s leases have remaining lease terms of 1 year to 14 years, some of which include options to extend the leases for up to 5 years.

The Company also has subleases of former corporate offices. Subleases have remaining lease terms of 1 year to 4 years. Sublease income, which is recorded as a reduction of rental expense, was $1.8 million and $5.3 million for the three and nine months ended September 30, 2019, respectively, and $2.8 million and $9.4 million for the three and nine months ended September 30, 2018, respectively.

The components of single lease cost were as follows:



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018
Operating lease cost ⁽¹⁾	$	27.4	$	21.4	$	75.9	$	64.4
Finance lease cost:
Amortization of assets under finance lease	18.2		21.9		60.4		66.0
Interest	2.3		2.1		6.8		5.9
Total finance lease cost	$	20.5	$	24.0	$	67.2	$	71.9

⁽¹⁾ Is presented gross of sublease income and includes short-term leases, which are immaterial

Other information related to leases was as follows:



		Nine months ended September 30, 2019
Supplemental Cash Flow Information:
Cash paid for amounts included in the measurement of lease liabilities:
Payments for operating leases included in cash from operating activities		74.6
Payments for finance leases included in cash from operating activities		6.8
Payments for finance leases included in cash from financing activities		71.8
Assets obtained in exchange for lease obligations:
Operating leases⁽²⁾		202.0
Finance leases		107.0

⁽²⁾ Includes the impact of the Company taking initial possession of the second phase of its new corporate headquarters in April of 2019 of $159.3 million.



	As of September 30, 2019

Weighted Average Remaining Lease Term (in years)
Operating leases	10.8
Finance leases	3.0

Weighted Average Discount Rate
Operating leases	4.4	%
Finance leases	4.6	%

Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows:



Year ending December 31,	Operating leases⁽¹⁾			Finance leases
2019 (excluding the nine months ended September 30, 2019)	$	26.9		$	22.8
2020	107.7			74.3
2021	96.5			59.1
2022	86.3			45.1
2023	69.7			11.6
Thereafter	545.6			—
Total future minimum lease payments	932.7			212.9
Less imputed interest	(213.1		)	(14.0		)
Less tenant improvement receivables	(17.4		)	—
Total liability	$	702.2		$	198.9

⁽¹⁾ Consists of future non-cancelable minimum rental payments under operating leases for the Company’s corporate offices and datacenters where the Company has possession, excluding rent payments from the Company’s sub-tenants and variable operating expenses. As of September 30, 2019, the Company is entitled to non-cancelable rent payments from its sub-tenants of $38.3 million, which will be collected over the next 1 to 4 years.

In 2017, the Company entered into a lease agreement for office space in San Francisco, California, to serve as its new corporate headquarters. The Company took initial possession of the first phase of its new corporate headquarters in June 2018, and began to recognize single lease cost related to the first phase. In that same period, the Company recorded a lease incentive obligation related to tenant improvement reimbursements associated with the first phase. In April 2019, the Company took possession of the second phase, and began to recognize additional lease costs and recorded an additional lease obligation, net of tenant improvement reimbursements related to the second phase. The Company's total expected minimum obligations for all three phases of the lease are $838.9 million, which exclude expected tenant improvement reimbursements from the landlord of approximately $75.0 million and variable operating expenses. The Company’s obligations under the lease are supported by a $34.2 million letter of credit, which reduced the borrowing capacity under the revolving credit facility. In the nine months ended September 30, 2019, the Company collected tenant improvement reimbursements from the landlord totaling $45.4 million.

In the third quarter of 2019, the Company relocated from its former corporate headquarters to its new corporate headquarters and began to make recurring rental payments for its new corporate headquarters.

As of September 30, 2019, the Company had commitments of $220.2 million for operating leases that have not yet commenced, and therefore are not included in the right-of-use asset or operating lease liability. These operating leases will commence between 2019 and 2021 with lease terms of 4 years to 14 years.

Leases

The components of single lease cost were as follows:



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018
Operating lease cost ⁽¹⁾	$	27.4	$	21.4	$	75.9	$	64.4
Finance lease cost:
Amortization of assets under finance lease	18.2		21.9		60.4		66.0
Interest	2.3		2.1		6.8		5.9
Total finance lease cost	$	20.5	$	24.0	$	67.2	$	71.9

⁽¹⁾ Is presented gross of sublease income and includes short-term leases, which are immaterial

Other information related to leases was as follows:



		Nine months ended September 30, 2019
Supplemental Cash Flow Information:
Cash paid for amounts included in the measurement of lease liabilities:
Payments for operating leases included in cash from operating activities		74.6
Payments for finance leases included in cash from operating activities		6.8
Payments for finance leases included in cash from financing activities		71.8
Assets obtained in exchange for lease obligations:
Operating leases⁽²⁾		202.0
Finance leases		107.0

⁽²⁾ Includes the impact of the Company taking initial possession of the second phase of its new corporate headquarters in April of 2019 of $159.3 million.



	As of September 30, 2019

Weighted Average Remaining Lease Term (in years)
Operating leases	10.8
Finance leases	3.0

Weighted Average Discount Rate
Operating leases	4.4	%
Finance leases	4.6	%

Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows:



Year ending December 31,	Operating leases⁽¹⁾			Finance leases
2019 (excluding the nine months ended September 30, 2019)	$	26.9		$	22.8
2020	107.7			74.3
2021	96.5			59.1
2022	86.3			45.1
2023	69.7			11.6
Thereafter	545.6			—
Total future minimum lease payments	932.7			212.9
Less imputed interest	(213.1		)	(14.0		)
Less tenant improvement receivables	(17.4		)	—
Total liability	$	702.2		$	198.9

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal matters From time to time, the Company is a party to a variety of claims, lawsuits, and proceedings which arise in the ordinary course of business, including claims of alleged infringement of intellectual property rights. The Company records a liability when it believes that it is probable that a loss will be incurred and the amount of loss or range of loss can be reasonably estimated. In its opinion, resolution of pending matters is not likely to have a material adverse impact on its condensed consolidated results of operations, cash flows, or its financial position. Given the unpredictable nature of legal proceedings, the Company bases its estimate on the information available at the time of the assessment. As additional information becomes available, the Company reassesses the potential liability and may revise the estimate. Indemnification The Company’s arrangements generally include certain provisions for indemnifying customers against liabilities if its products or services infringe a third party’s intellectual property rights. It is not possible to determine the maximum potential amount under these indemnification obligations due to the limited history of prior indemnification claims. Other commitments Other commitments include payments to third-party vendors for services related to the Company’s infrastructure, infrastructure warranty contracts, and asset retirement obligations for office modifications. There have been no material changes in the Company's other commitments, as disclosed in the Annual Report.

Accrued and Other Current Liabilities

9 Months Ended

Sep. 30, 2019

Payables and Accruals [Abstract]

Accrued and Other Current Liabilities

Accrued and other current liabilities consisted of the following:



	As of
	September 30, 2019		December 31, 2018

Non-income taxes payable	$	88.3	$	75.7
Accrued legal and other external fees	28.9		28.1
Deferred rent	—		41.0
Other accrued and current liabilities	32.7		19.7
Total accrued and other current liabilities	$	149.9	$	164.5

The decrease in deferred rent from December 31, 2018 is due to the Company's adoption of ASC 842 on January 1, 2019 using the modified retrospective approach. As of September 30, 2019, deferred rent reduces the Company's operating right-of-use asset. See Note 9 "Leases" for additional discussion.

Stockholders' Equity

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Stockholders' Equity

Stockholders’ Equity

Common stock

The Company’s amended and restated certificate of incorporation authorizes the issuance of Class A common stock, Class B common stock, and Class C common stock. Holders of Class A common stock, Class B common stock, and Class C common stock are entitled to dividends on a pro rata basis, when, as, and if declared by the Company’s Board of Directors, subject to the rights of the holders of the Company’s preferred stock. Holders of Class A common stock are entitled to one vote per share, holders of Class B common stock are entitled to 10 votes per share, and holders of Class C common stock are entitled to zero votes per share.

Holders of Class B common stock voluntarily converted 0.7 million and 38.4 million shares into an equivalent number shares of Class A common stock during the three and nine months ended September 30, 2019, respectively, and 61.3 million during the three and nine months ended September 30, 2018, respectively.

As of September 30, 2019, the Company had authorized 2,400.0 million shares of Class A common stock, 475.0 million shares of Class B common stock, and 800.0 million shares of Class C common stock, each at par value of $0.00001. As of September 30, 2019, 253.9 million shares of Class A common stock, 161.4 million shares of Class B common stock, and no shares of Class C common stock were issued and outstanding. As of December 31, 2018, 211.0 million shares of Class A common stock, 198.6 million shares of Class B common stock, and no shares of Class C common stock were issued and outstanding. Class A shares issued and outstanding as of September 30, 2019 and December 31, 2018 exclude 14.7 million unvested restricted stock awards granted to the Company’s co-founders. See "Co-Founder Grants" section below for further details.

Convertible preferred stock

Immediately prior to the closing of the Company’s IPO, all of the 147.3 million shares of convertible preferred stock converted into an equivalent number of shares of Class B common stock. Further, pursuant to transfer agreements with certain of the Company’s stockholders, 0.3 million shares of the Company’s convertible preferred stock automatically converted into an equivalent number of shares of Class A common stock.

Preferred stock

The Company's Board of Directors will have the authority, without further action by the Company's stockholders, to issue up to 240.0 million shares of undesignated preferred stock with rights and preferences, including voting rights, designated from time to time by the Board of Directors.

Equity incentive plans

Under the 2018 Plan, the Company may grant stock-based awards to purchase or directly issue shares of common stock to employees, directors, and consultants. Options are granted at a price per share equal to the fair market value of the Company's common stock at the date of grant. Options granted are exercisable over a maximum term of 10 years from the date of grant and generally vest over a period of four years. RSUs and RSAs are also granted under the 2018 Plan. The 2018 Plan will terminate 10 years after the later of (i) its adoption or (ii) the most recent stockholder-approved increase in the number of shares reserved under the 2018 Plan, unless terminated earlier by the Company's Board of Directors. The 2018 Plan was adopted on March 22, 2018.

In connection with the acquisition of HelloSign, the Company assumed unvested stock options that had been granted under HelloSign's 2011 Equity Incentive Plan.

As of September 30, 2019, there were 31.3 million stock-based awards issued and outstanding and 69.4 million shares available for issuance under the Dropbox Equity Incentive Plans and HelloSign's 2011 Equity Incentive Plan (collectively, the "Plans").

Stock option and restricted stock activity for the Plans was as follows for the nine months ended September 30, 2019:



			Options outstanding							Restricted stock outstanding
	Number of shares available for issuance under the Plans		Number of shares outstanding under the Plans		Weighted- average exercise price per share		Weighted- average remaining contractual term (In years)	Aggregate intrinsic value		Number of shares outstanding under the Plans		Weighted- average grant date fair value per share

Balance at December 31, 2018	57.1		1.3		$	14.68	5.0	$	9.1	25.0		$	18.68
Additional shares authorized	21.2		—		—					—		—
Stock options assumed	0.9		0.9		6.02					—		—
Options exercised and RSUs released	—		(0.3	)	7.07					(8.5	)	18.90
Options and RSUs canceled	5.2		(0.2	)	19.16					(5.0	)	18.78
Shares repurchased for tax withholdings on release of restricted stock	3.1		—		—					—		18.87
Restricted stock and options granted	(18.1	)	0.2		22.63					17.9		22.03
Balance at September 30, 2019	69.4		1.9		$	12.26	6.8	$	17.6	29.4		$	20.64
Vested at September 30, 2019			1.2		$	16.05	5.6	$	7.0	—		$	—
Unvested at September 30, 2019			0.7		$	6.15		$	10.6	29.4		$	20.64

The following table summarizes information about the pre-tax intrinsic value of options exercised during the three and nine months ended September 30, 2019 and 2018:



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018

Intrinsic value of options exercised	$	0.3	$	32.0	$	4.8	$	34.0

As of September 30, 2019, unamortized stock-based compensation related to unvested stock options, restricted stock awards (excluding the Co-Founder Grants), and RSUs was $583.6 million. The weighted-average period over which such compensation expense will be recognized if the requisite service is provided is approximately 2.9 years as of September 30, 2019.

The total fair value of released RSUs, as of their respective vesting dates, were $52.6 million and $184.0 million during the three and nine months ended September 30, 2019, respectively, and $92.0 million and $847.1 million during the three and nine months ended September 30, 2018, respectively.

Assumed stock options

In connection with the acquisition of HelloSign the Company assumed 0.9 million unvested stock options which were valued using the Black-Scholes option-pricing model. The fair value of stock options assumed were estimated using the following assumptions:



Expected volatility	51.6	%
Expected term (in years)	3.4 - 7.0
Risk-free interest rate	2.42% - 2.51%
Dividend yield	—	%

Expected volatility. The expected volatility is based on the Company's historical volatility. Management believes this is the best estimate of the expected volatility over the expected life of its stock options.

Expected term. The Company determines the expected term based on the average period the stock options are expected to remain outstanding, generally calculated as the midpoint of the stock options’ remaining vesting term and contractual expiration period, as the Company does not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior.

Risk-free interest rate. The risk-free interest rate is based on the U.S. Treasury security in effect at the time the options were assumed for maturities corresponding with the expected term of the option.

Expected dividend yield. The Company has not paid and does not expect to pay dividends. Consequently, the Company uses an expected dividend yield of zero.

The estimated weighted-average grant date fair value for stock options assumed was $21.60 per share and total fair value of $19.4 million, of which, $18.6 million will be recognized as post-combination stock-based compensation expense.

Co-Founder Grants

In December 2017, the Board of Directors approved a grant to the Company’s co-founders of non-Plan RSAs with respect to 14.7 million shares of Class A Common Stock in the aggregate (collectively, the “Co-Founder Grants”), of which 10.3 million RSAs were granted to Mr. Houston, the Company’s co-founder and Chief Executive Officer, and 4.4 million RSAs were granted to Mr. Ferdowsi, the Company’s co-founder and Director. These Co-Founder Grants have service-based, market-based, and performance-based vesting conditions. The Co-Founder Grants are excluded from Class A common stock issued and outstanding until the satisfaction of these vesting conditions. The Co-Founder Grants also provide the holders with certain stockholder rights, such as the right to vote the shares with the other holders of Class A common stock and a right to cumulative declared dividends. However, the Co-Founder Grants are not considered a participating security for purposes of calculating net loss per share attributable to common stockholders in Note 13, "Net Loss Per Share", as the right to the cumulative declared dividends is forfeitable if the service condition is not met.

The Co-Founder Grants are eligible to vest over the ten-year period following the date the Company’s shares of Class A common stock commenced trading on the Nasdaq Global Select Market in connection with the Company’s IPO. The Co-Founder Grants comprise nine tranches that are eligible to vest based on the achievement of stock price goals, each of which are referred to as a Stock Price Target, measured over a consecutive thirty-day trading period during the Performance Period. The Performance Period began on January 1, 2019.

During the first four years of the Performance Period, no more than 20% of the shares subject to each Co-Founder Grant would be eligible to vest in any calendar year. After the first four years, all shares are eligible to vest based on the achievement of the Stock Price Targets.

The Company calculated the grant date fair value of the Co-Founder Grants based on multiple stock price paths developed through the use of a Monte Carlo simulation. A Monte Carlo simulation also calculates a derived service period for each of the nine vesting tranches, which is the measure of the expected time to achieve each Stock Price Target. A Monte Carlo simulation requires the use of various assumptions, including the underlying stock price, volatility, and the risk-free interest rate as of the valuation date, corresponding to the length of time remaining in the performance period, and expected dividend yield. The weighted-average grant date fair value of each Co-Founder Grant was estimated to be $10.60 per share. The weighted-average derived service period of each Co-Founder Grant was estimated to be 5.2 years, and ranged from 2.9 - 6.9 years. The Company will recognize aggregate stock-based compensation expense of $156.2 million over the derived service period of each tranche using the accelerated attribution method as long as the co-founders satisfy their service-based vesting conditions. If the Stock Price Targets are met sooner than the derived service period, the Company will adjust its stock-based compensation to reflect the cumulative expense associated with the vested awards. The Company will recognize expense if the requisite service is provided, regardless of whether the market conditions are achieved.

The Performance Vesting Condition for the Co-Founder Grants was satisfied on the date the Company’s shares of Class A common stock commenced trading on the Nasdaq Global Select Market in connection with the Company’s IPO, which was March 23, 2018. The Company recognized stock-based compensation expense related to the Co-Founder Grants of $8.8 million and $26.1 million during the three and nine months ended September 30, 2019, respectively, and $8.8 million and $28.1 million during the three and nine months ended September 30, 2018, respectively. As of September 30, 2019, unamortized stock-based compensation expense related to the Co-Founder Grants was $93.1 million.

Award modifications

During the year ended December 31, 2017, the Company's Board of Directors voted to approve a modification of vesting schedules for certain unvested one-tier and two-tier RSUs to align the vesting schedules for all RSUs to vest once per quarter. The modification was effective February 15, 2018, which resulted in accelerated vesting of impacted RSUs that had met their service requirement as of that date. As a result, the Company recognized an incremental $10.0 million in stock-based compensation during the first quarter of 2018 related to these modified one-tier and two-tier RSUs.

Net Loss Per Share

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Net Loss Per Share

The Company computes net loss per share using the two-class method required for multiple classes of common stock and participating securities. The rights, including the liquidation and dividend rights, of the Class A common stock and Class B common stock are substantially identical, other than voting rights. Accordingly, the Class A common stock and Class B common stock share equally in the Company’s net losses. Before the IPO, the Company’s outstanding securities also included convertible preferred stock. The holders of convertible preferred stock did not have a contractual obligation to share in the Company’s losses, and as a result, net losses were not allocated to these securities.

The following table sets forth the calculation of basic and diluted net loss per share attributable to common stockholders during the periods presented. The shares issued in the IPO and the shares of Class A and Class B common stock issued upon conversion of the outstanding shares of convertible preferred stock in the IPO are included in the table below weighted for the period outstanding in the three and nine months ended September 30, 2018. Additionally, the voluntary conversions of Class B common stock into Class A common stock are included in the table below weighted for the period outstanding in the three and nine months ended September 30, 2019 and 2018:



	Three months ended September 30,
	2019						2018
	Class A			Class B			Class A			Class B

Numerator:
Net loss attributable to common stockholders	$	(10.4	)	$	(6.6	)	$	(1.9	)	$	(3.9	)
Denominator:
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share	252.7			161.7			133.2			270.7
Net loss per common share, basic and diluted	$	(0.04	)	$	(0.04	)	$	(0.01	)	$	(0.01	)



	Nine months ended September 30,
	2019						2018
	Class A			Class B			Class A			Class B

Numerator:
Net loss attributable to common stockholders	$	(26.1	)	$	(20.0	)	$	(105.5	)	$	(369.9	)
Denominator:
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share	233.1			179.3			75.9			266.1
Net loss per common share, basic and diluted	$	(0.11	)	$	(0.11	)	$	(1.39	)	$	(1.39	)

Since the Company was in a loss position for all periods presented, basic net loss per share attributable to common stockholders is the same as diluted net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. The weighted-average impact of potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive was as follows:



	Three months ended September 30,		Nine months ended September 30,
	2019	2018	2019	2018

Restricted stock units	30.1	28.7	28.7	38.0
Options to purchase shares of common stock	1.9	4.3	1.9	4.7
Co-Founder Grants	14.7	14.7	14.7	14.7
Shares subject to repurchase from early-exercised options and unvested restricted stock	—	—	—	0.1
Total	46.7	47.7	45.3	57.5

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company computed the year-to-date income tax provision by applying the estimated annual effective tax rate to the year-to-date pre-tax loss and adjusted for discrete tax items in the period. The Company's income tax was an expense of $1.6 million and a benefit of $3.5 million for the three and nine months ended September 30, 2019, respectively, and a benefit of $0.2 million and an expense of $2.7 million for the three and nine months ended September 30, 2018, respectively. The income tax benefit for the nine months ended September 30, 2019 was primarily attributable to the tax benefit from the acquisition of HelloSign. During the nine months ended September 30, 2019, the Company recorded a deferred tax liability of $6.9 million to reflect the tax effect of the assets and liabilities recorded in the acquisition of HelloSign. Due to the acquisition of HelloSign, the Company recorded a one-time benefit of $6.9 million to recognize previously unrecognized deferred tax assets, which are now more-likely-than-not to be realized as a result of the net deferred tax liability recorded in the transaction. For further discussion of the HelloSign acquisition, see Note 5 "Business Combinations". For the periods presented, the difference between the U.S. statutory rate and the Company's effective tax rate is primarily due to the full valuation allowance on its U.S. and Irish deferred tax assets. The effective tax rate is also impacted by earnings realized in foreign jurisdictions with statutory tax rates lower than the federal statutory tax rate. The Company periodically evaluates the realizability of its net deferred tax assets based on all available evidence, both positive and negative. The realization of net deferred tax assets is dependent on the Company's ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. As of September 30, 2019, the Company continues to maintain a full valuation allowance on its deferred tax assets in the U.S. and Ireland. However, the Company has partially benefited from its deferred tax assets due to the recognition of forecasted future income which is more likely than not to be earned in one of its foreign jurisdictions. The Company is subject to income tax audits in the U.S. and foreign jurisdictions. The Company records liabilities related to uncertain tax positions and believes that it has provided adequate reserves for income tax uncertainties in all open tax years. Unrecognized tax benefits increased by approximately $9.6 million for the nine months ended September 30, 2019, of which $1.5 million, if recognized, would affect the Company's effective tax rate.

Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Dropbox Charitable Foundation During the year ended December 31, 2016, two of the Company’s controlling shareholders formed the Dropbox Charitable Foundation, a Delaware non-stock corporation (the “Foundation”). The primary purpose of the Foundation is to engage in charitable and educational activities within the meaning of Section 501(c)(3) of the Code. The Foundation is governed by a Board of Directors, a majority of which are independent. Both shareholders made contributions to the Foundation during the year ended December 31, 2016, comprised entirely of shares of Dropbox common stock. The Company has not consolidated the Foundation in the accompanying condensed consolidated financial statements, as the Company does not have control of the entity. There were no contributions to the Foundation during the three and nine months ended September 30, 2019 and 2018, respectively.

Geographic Areas

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Geographic Areas

Long-lived assets

The following table sets forth long-lived assets by geographic area:



	As of
	September 30, 2019		December 31, 2018

United States	$	403.0	$	293.6
International⁽¹⁾	13.6		17.0
Total property and equipment, net	$	416.6	$	310.6


⁽¹⁾	No single country other than the United States had a property and equipment balance greater than 10% of total property and equipment, net, as of September 30, 2019 and December 31, 2018.

Revenue

Revenue by geography is generally based on the address of the customer as defined in the Company’s subscription agreement. The following table sets forth revenue by geographic area for the three and nine months ended September 30, 2019 and 2018.



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018

United States	$	220.8	$	182.6	$	623.4	$	516.5
International⁽¹⁾	207.4		177.7		591.9		499.3
Total revenue	$	428.2	$	360.3	$	1,215.3	$	1,015.8

⁽¹⁾

No single country outside of the United States accounted for more than 10% of total revenue during the three and nine months ended September 30, 2019 and 2018.

Description of the Business and Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of presentation

Basis of consolidation

Use of estimates

Financial information about segments and geographic areas

Foreign currency transactions

Revenue recognition and deferred commissions, net


•	Identification of the contract, or contracts, with a customer


•	Identification of the performance obligations in the contract


•	Determination of the transaction price


•	Allocation of the transaction price to the performance obligations in the contract


•	Recognition of revenue when, or as, the Company satisfies a performance obligation

The price of subscriptions is generally fixed at contract inception and therefore, the Company’s contracts do not contain a significant amount of variable consideration.

Stock-based compensation

•

As of September 30, 2019, the Company only had one-tier RSUs outstanding under the Dropbox Equity Incentive Plans.

underlying common stock based on the closing price of the Company's Class A common stock as reported on the Nasdaq Global Select Market on the date of the grant.

Cash and cash equivalents

Short-term investments

Concentrations of credit risk

Trade accounts receivables are typically unsecured and are derived from revenue earned from customers located around the world.

Non-trade receivables

Property and equipment, net

The following table presents the estimated useful lives of property and equipment:



Property and equipment		Useful life

Datacenter and other computer equipment		3 to 5 years
Office equipment and other		3 to 7 years
Leasehold improvements		Lesser of estimated useful life or remaining lease term

Lease obligations

Business combinations

Long-lived assets, including goodwill and other acquired intangible assets, net

The Company has not recorded impairment charges on property and equipment, goodwill, or intangible assets for the periods presented in these condensed consolidated financial statements.

Income taxes

Fair value measurement

Level 1—Quoted prices in active markets for identical assets or liabilities.

Level 3—Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

Recently issued accounting pronouncements not yet adopted and Recently adopted accounting pronouncements

Goodwill

Goodwill represents the excess of the purchase price in a business combination over the fair value of net tangible and intangible assets acquired. Goodwill amounts are not amortized, but tested for impairment on an annual basis.

Net loss per share

Description of the Business and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Estimated Useful Lives of Property and Equipment

The following table presents the estimated useful lives of property and equipment:



Property and equipment		Useful life

Datacenter and other computer equipment		3 to 5 years
Office equipment and other		3 to 7 years
Leasehold improvements		Lesser of estimated useful life or remaining lease term

Property and equipment, net consisted of the following:



	As of
	September 30, 2019			December 31, 2018

Datacenter and other computer equipment	$	741.9		$	667.4
Furniture and fixtures	34.6			23.8
Leasehold improvements	203.6			150.5
Construction in process	19.7			32.8
Total property and equipment	999.8			874.5
Accumulated depreciation and amortization	(583.2		)	(563.9		)
Property and equipment, net	$	416.6		$	310.6

Cash, Cash Equivalents and Short-Term Investments (Tables)

9 Months Ended

Sep. 30, 2019

Cash and Cash Equivalents [Abstract]

Schedule of Cash, Cash Equivalents and Short-Term Investments



	As of September 30, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value

Cash	$	102.0	$	—	$	—		$	102.0
Cash equivalents:
Money market funds	333.2		—		—			333.2
U.S. Treasury securities	7.0		—		—			7.0
Asset-backed securities	1.0		—		—			1.0
Total cash and cash equivalents	$	443.2	$	—	$	—		$	443.2
Short-term investments
Corporate notes and obligations	258.5		1.4		—			259.9
U.S. Treasury securities	176.1		0.3		(0.1		)	176.3
Certificates of deposit	44.9		—		—			44.9
Asset-backed securities	44.8		—		(0.1		)	44.7
Commercial Paper	34.4		—		—			34.4
U.S. agency obligations	25.1		—		—			25.1
Municipal securities	2.4		—		—			2.4
Total short-term investments	586.2		1.7		(0.2		)	587.7
Total	$	1,029.4	$	1.7	$	(0.2	)	$	1,030.9



	As of December 31, 2018
	Amortized cost		Unrealized gain		Unrealized loss			Estimated fair value

Cash	$	103.0	$	—	$	—		$	103.0
Cash equivalents
Money market funds	355.5		—		—			355.5
U.S. Treasury securities	33.4		—		—			$	33.4
Commercial paper	27.4		—		—			27.4
Total cash and cash equivalents	$	519.3	$	—	$	—		$	519.3
Short-term investments
Corporate notes and obligations	269.6		0.1		(0.5		)	269.2
U.S. Treasury securities	176.0		—		(0.1		)	175.9
Certificates of deposit	70.6		—		—			70.6
U.S. agency obligations	37.1		—		—			37.1
Commercial paper	17.2		—		—			17.2
Total short-term investments	570.5		0.1		(0.6		)	570.0
Total	$	1,089.8	$	0.1	$	(0.6	)	$	1,089.3

Contractual Maturities of Short Term Investments

The following table presents the contractual maturities of the Company’s short-term investments as of September 30, 2019:



	As of September 30, 2019
	Amortized cost		Estimated fair value

Due within one year	$	261.5	$	261.9
Due between one to three years	324.7		325.8
Total	$	586.2	$	587.7

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets Measured On Recurring Basis

The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis using the input categories discussed in Note 1:



	As of September 30, 2019
	Level 1		Level 2		Level 3		Total

Cash equivalents
Money market funds	$	333.2	$	—	$	—	$	333.2
U.S. Treasury securities	—		7.0		—		7.0
Asset-backed securities	—		1.0		—		1.0
Total cash equivalents	$	333.2	$	8.0	$	—	$	341.2
Short-term investments
Corporate notes and obligations	—		259.9		—		259.9
U.S. Treasury securities	—		176.3		—		176.3
Certificates of deposit	—		44.9		—		44.9
Asset-backed securities	—		44.7		—		44.7
Commercial paper	—		34.4		—		34.4
U.S. agency obligations	—		25.1		—		25.1
Municipal securities	—		2.4		—		2.4
Total short-term investments	—		587.7		—		587.7
Equity investments	10.7		—		—		10.7
Total	$	343.9	$	595.7	$	—	$	939.6



	As of December 31, 2018
	Level 1		Level 2		Level 3		Total

Cash equivalents
Money market funds	$	355.5	$	—	$	—	$	355.5
U.S. Treasury securities	—		33.4		—		33.4
Commercial paper	—		27.4		—		27.4
Total cash equivalents	$	355.5	$	60.8	—		$	416.3
Short-term investments
Corporate notes and obligations	—		269.2		—		269.2
U.S. Treasury securities	—		175.9		—		175.9
Certificates of deposit	—		70.6		—		70.6
U.S agency obligations	—		37.1		—		37.1
Commercial paper	—		17.2		—		17.2
Total short-term investments	—		570.0		—		570.0
Total	$	355.5	$	630.8	$	—	$	986.3

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2019

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

The following table presents the estimated useful lives of property and equipment:



Property and equipment		Useful life

Datacenter and other computer equipment		3 to 5 years
Office equipment and other		3 to 7 years
Leasehold improvements		Lesser of estimated useful life or remaining lease term

Property and equipment, net consisted of the following:



	As of
	September 30, 2019			December 31, 2018

Datacenter and other computer equipment	$	741.9		$	667.4
Furniture and fixtures	34.6			23.8
Leasehold improvements	203.6			150.5
Construction in process	19.7			32.8
Total property and equipment	999.8			874.5
Accumulated depreciation and amortization	(583.2		)	(563.9		)
Property and equipment, net	$	416.6		$	310.6

Business Combinations (Tables)

9 Months Ended

Sep. 30, 2019

Business Combinations [Abstract]

Schedule of Purchase Consideration Transferred

The purchase consideration transferred consisted of the following:



	Purchase consideration
Cash paid to common and preferred stockholders and vested option holders	$	175.2
Transaction costs paid by Dropbox on behalf of HelloSign	2.4
Fair value of assumed HelloSign options attributable to pre-combination services ⁽¹⁾	0.8
Purchase price adjustments	(0.5		)
Total purchase consideration	$	177.9

⁽¹⁾The fair value of options assumed were based upon the Black-Scholes option-pricing model.

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed



Assets acquired:
Cash and cash equivalents	$	5.5
Short-term investments	7.8
Acquisition-related intangible assets	44.6
Accounts receivable, prepaid and other assets	5.0
Total assets acquired	$	62.9

Liabilities assumed:
Accounts payable, accrued and other liabilities	$	6.3
Deferred revenue	4.8
Deferred tax liability	6.9
Total liabilities assumed	18.0
Net assets acquired, excluding goodwill	44.9
Total purchase consideration	177.9
Estimated goodwill ⁽²⁾	$	133.0

⁽²⁾ The goodwill recognized was primarily attributable to the opportunity to expand the user base of the Company's platform. The goodwill is not deductible for U.S. federal income tax purposes.

Schedule of Finite-Lived Intangible Assets Acquired and Estimated Useful Lives

The fair value of the separately identifiable finite-lived intangible assets acquired and estimated weighted average useful lives are as follows:



	Estimated fair values		Estimated weighted average useful lives (In years)
Customer relationships	$	20.5	4.9
Developed technology	19.6		5.0
Trade name	4.5		5.0
Total acquisition-related intangible assets	$	44.6

Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

Intangible assets consisted of the following:



	As of September 30,			As of December 31,			Weighted- average remaining useful life (In years)
	2019			2018			Weighted- average remaining useful life (In years)
Developed technology	$	25.0		$	47.0		4.4
Customer relationships	20.5			—			4.3
Software	20.0			19.2			1.8
Patents	13.0			13.0			7.7
Assembled workforce in asset acquisitions	12.6			12.6			1.3
Licenses	4.6			4.6			1.8
Trademarks and trade names	5.2			0.7			4.4
Other	3.3			3.3			5.8
Total intangibles	104.2			100.4
Accumulated amortization	(54.1		)	(85.7		)
Intangible assets, net	$	50.1		$	14.7

Schedule of Future Amortization Expense

Expected future amortization expense for intangible assets as of September 30, 2019, is as follows:




Remaining three months of Fiscal 2019	$	3.6
2020	13.6
2021	11.3
2022	8.0
2023	7.7
Thereafter	5.9
Total	$	50.1

Goodwill (Tables)

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The changes in the carrying amounts of goodwill were as follows:



Balance at December 31, 2018	$	96.5
HelloSign acquisition	133.0
Effect of foreign currency translation	2.3
Balance at September 30, 2019	$	231.8

Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Components of Lease Expense and Other Information

The components of single lease cost were as follows:



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018
Operating lease cost ⁽¹⁾	$	27.4	$	21.4	$	75.9	$	64.4
Finance lease cost:
Amortization of assets under finance lease	18.2		21.9		60.4		66.0
Interest	2.3		2.1		6.8		5.9
Total finance lease cost	$	20.5	$	24.0	$	67.2	$	71.9

⁽¹⁾ Is presented gross of sublease income and includes short-term leases, which are immaterial

Other information related to leases was as follows:



		Nine months ended September 30, 2019
Supplemental Cash Flow Information:
Cash paid for amounts included in the measurement of lease liabilities:
Payments for operating leases included in cash from operating activities		74.6
Payments for finance leases included in cash from operating activities		6.8
Payments for finance leases included in cash from financing activities		71.8
Assets obtained in exchange for lease obligations:
Operating leases⁽²⁾		202.0
Finance leases		107.0

⁽²⁾ Includes the impact of the Company taking initial possession of the second phase of its new corporate headquarters in April of 2019 of $159.3 million.



	As of September 30, 2019

Weighted Average Remaining Lease Term (in years)
Operating leases	10.8
Finance leases	3.0

Weighted Average Discount Rate
Operating leases	4.4	%
Finance leases	4.6	%

Maturities of Operating Lease Liabilities

Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows:



Year ending December 31,	Operating leases⁽¹⁾			Finance leases
2019 (excluding the nine months ended September 30, 2019)	$	26.9		$	22.8
2020	107.7			74.3
2021	96.5			59.1
2022	86.3			45.1
2023	69.7			11.6
Thereafter	545.6			—
Total future minimum lease payments	932.7			212.9
Less imputed interest	(213.1		)	(14.0		)
Less tenant improvement receivables	(17.4		)	—
Total liability	$	702.2		$	198.9

Maturities of Finance Lease Liabilities

Future minimum lease payments under non-cancellable leases as of September 30, 2019 were as follows:



Year ending December 31,	Operating leases⁽¹⁾			Finance leases
2019 (excluding the nine months ended September 30, 2019)	$	26.9		$	22.8
2020	107.7			74.3
2021	96.5			59.1
2022	86.3			45.1
2023	69.7			11.6
Thereafter	545.6			—
Total future minimum lease payments	932.7			212.9
Less imputed interest	(213.1		)	(14.0		)
Less tenant improvement receivables	(17.4		)	—
Total liability	$	702.2		$	198.9

Accrued and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2019

Payables and Accruals [Abstract]

Schedule Of Accrued And Other Current Liabilities

Accrued and other current liabilities consisted of the following:



	As of
	September 30, 2019		December 31, 2018

Non-income taxes payable	$	88.3	$	75.7
Accrued legal and other external fees	28.9		28.1
Deferred rent	—		41.0
Other accrued and current liabilities	32.7		19.7
Total accrued and other current liabilities	$	149.9	$	164.5

Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Schedule of Stock Option and Restricted Stock Activity

Stock option and restricted stock activity for the Plans was as follows for the nine months ended September 30, 2019:



			Options outstanding							Restricted stock outstanding
	Number of shares available for issuance under the Plans		Number of shares outstanding under the Plans		Weighted- average exercise price per share		Weighted- average remaining contractual term (In years)	Aggregate intrinsic value		Number of shares outstanding under the Plans		Weighted- average grant date fair value per share

Balance at December 31, 2018	57.1		1.3		$	14.68	5.0	$	9.1	25.0		$	18.68
Additional shares authorized	21.2		—		—					—		—
Stock options assumed	0.9		0.9		6.02					—		—
Options exercised and RSUs released	—		(0.3	)	7.07					(8.5	)	18.90
Options and RSUs canceled	5.2		(0.2	)	19.16					(5.0	)	18.78
Shares repurchased for tax withholdings on release of restricted stock	3.1		—		—					—		18.87
Restricted stock and options granted	(18.1	)	0.2		22.63					17.9		22.03
Balance at September 30, 2019	69.4		1.9		$	12.26	6.8	$	17.6	29.4		$	20.64
Vested at September 30, 2019			1.2		$	16.05	5.6	$	7.0	—		$	—
Unvested at September 30, 2019			0.7		$	6.15		$	10.6	29.4		$	20.64

Schedule of Pre-Tax Intrinsic Value

The following table summarizes information about the pre-tax intrinsic value of options exercised during the three and nine months ended September 30, 2019 and 2018:



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018

Intrinsic value of options exercised	$	0.3	$	32.0	$	4.8	$	34.0

Fair Value of Stock Options Assumptions Used

The fair value of stock options assumed were estimated using the following assumptions:



Expected volatility	51.6	%
Expected term (in years)	3.4 - 7.0
Risk-free interest rate	2.42% - 2.51%
Dividend yield	—	%

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted



	Three months ended September 30,
	2019						2018
	Class A			Class B			Class A			Class B

Numerator:
Net loss attributable to common stockholders	$	(10.4	)	$	(6.6	)	$	(1.9	)	$	(3.9	)
Denominator:
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share	252.7			161.7			133.2			270.7
Net loss per common share, basic and diluted	$	(0.04	)	$	(0.04	)	$	(0.01	)	$	(0.01	)



	Nine months ended September 30,
	2019						2018
	Class A			Class B			Class A			Class B

Numerator:
Net loss attributable to common stockholders	$	(26.1	)	$	(20.0	)	$	(105.5	)	$	(369.9	)
Denominator:
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share	233.1			179.3			75.9			266.1
Net loss per common share, basic and diluted	$	(0.11	)	$	(0.11	)	$	(1.39	)	$	(1.39	)

Schedule of Potentially Dilutive Securities Excluded from Computation of Earnings Per Share

The weighted-average impact of potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive was as follows:



	Three months ended September 30,		Nine months ended September 30,
	2019	2018	2019	2018

Restricted stock units	30.1	28.7	28.7	38.0
Options to purchase shares of common stock	1.9	4.3	1.9	4.7
Co-Founder Grants	14.7	14.7	14.7	14.7
Shares subject to repurchase from early-exercised options and unvested restricted stock	—	—	—	0.1
Total	46.7	47.7	45.3	57.5

Geographic Areas (Tables)

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Long-lived Assets by Geographic Areas

The following table sets forth long-lived assets by geographic area:



	As of
	September 30, 2019		December 31, 2018

United States	$	403.0	$	293.6
International⁽¹⁾	13.6		17.0
Total property and equipment, net	$	416.6	$	310.6

⁽¹⁾

No single country other than the United States had a property and equipment balance greater than 10% of total property and equipment, net, as of September 30, 2019 and December 31, 2018.

Revenue by Geographic Areas

The following table sets forth revenue by geographic area for the three and nine months ended September 30, 2019 and 2018.



	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018

United States	$	220.8	$	182.6	$	623.4	$	516.5
International⁽¹⁾	207.4		177.7		591.9		499.3
Total revenue	$	428.2	$	360.3	$	1,215.3	$	1,015.8

⁽¹⁾

No single country outside of the United States accounted for more than 10% of total revenue during the three and nine months ended September 30, 2019 and 2018.

Description of the Business and Summary of Significant Accounting Policies - Initial Public Offering, Private Placement, and Stock Split (Details) $ / shares in Units, $ in Millions							3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 03, 2018 USD ($)	Mar. 28, 2018 USD ($) $ / shares shares	Mar. 27, 2018 USD ($) $ / shares shares	Mar. 26, 2018 shares	Mar. 22, 2018 USD ($)	Mar. 07, 2018	Sep. 30, 2019 shares	Sep. 30, 2018 shares	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($) shares	Dec. 31, 2018 USD ($)
Conversion of Stock [Line Items]
Stock issued in IPO (in shares)			26,822,409
Share price of stock issued in IPO (in dollars per share) \| $ / shares			$ 21.00
Proceeds from initial public offering and private placement \| $			$ 538.2						$ 0.0	$ 746.6	$ 746.6
Offering costs \| $			$ 6.9						$ 0.0	$ 4.5
Reverse stock split ratio						0.6667
Class B common stock
Conversion of Stock [Line Items]
Shares converted in conversion (in shares)							700,000	61,300,000	38,400,000	61,300,000
Conversion of Convertible Preferred Stock to Class B Common Stock \| Convertible preferred stock
Conversion of Stock [Line Items]
Shares converted in conversion (in shares)				147,310,563
Conversion of Convertible Preferred Stock to Class B Common Stock \| Class B common stock
Conversion of Stock [Line Items]
Shares issued in conversion (in shares)				147,310,563
Conversion of Convertible Preferred Stock to Class A Common Stock \| Convertible preferred stock
Conversion of Stock [Line Items]
Shares converted in conversion (in shares)				258,620
Conversion of Convertible Preferred Stock to Class A Common Stock \| Class A common stock
Conversion of Stock [Line Items]
Shares issued in conversion (in shares)				258,620
Conversion of Class B Common Stock to Class A Common Stock \| Class B common stock
Conversion of Stock [Line Items]
Shares converted in conversion (in shares)				2,609,951
Conversion of Class B Common Stock to Class A Common Stock \| Class A common stock
Conversion of Stock [Line Items]
Shares issued in conversion (in shares)				2,609,951
Private Placement
Conversion of Stock [Line Items]
Proceeds from initial public offering and private placement \| $		$ 100.0
Private Placement \| Class A common stock
Conversion of Stock [Line Items]
Sale of stock (in shares)		4,761,905
Share price of stock sold in shares (in dollars per share) \| $ / shares		$ 21.00
Underwriters Over-allotment Option \| Class A common stock
Conversion of Stock [Line Items]
Sale of stock (in shares)		5,400,000
Share price of stock sold in shares (in dollars per share) \| $ / shares		$ 21.00
Proceeds received in sale of stock \| $	$ 108.4
Two-Tier RSUs
Conversion of Stock [Line Items]
Recognized cumulative unrecognized stock-based compensation \| $					$ 418.7					$ 418.7
Shares released (in shares)										26,800,000
Employer related payroll expense \| $										$ 13.9

Description of the Business and Summary of Significant Accounting Policies - Foreign Currency Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Foreign currency transaction losses	$ 0.6	$ 1.0	$ 1.1	$ 1.4

Description of the Business and Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue, performance obligation, description of timing			one year or longer
Revenue recognized	$ 241.3	$ 213.2	$ 452.9	$ 390.1
Remaining performance obligation	$ 588.7		$ 588.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation satisfaction period	12 months		12 months

Description of the Business and Summary of Significant Accounting Policies - Stock-based Compensation (Details) - shares shares in Millions	1 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2019	Dec. 31, 2018
One-Tier RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)		17.9
Tranche One \| One-Tier RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		1 year
Co-Founder Grants \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	14.7	14.7	14.7
Co-Founder Grants \| Tranche One \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Chief Executive Officer \| Co-Founder Grants \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	10.3
Director \| Co-Founder Grants \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	4.4

Description of the Business and Summary of Significant Accounting Policies - Concentration of Credit Risk (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Concentration Risk [Line Items]
Amortization of deferred commissions	$ 4.6	$ 3.2	$ 12.7	$ 8.5
Trade and Other Receivables \| Customer Concentration Risk \| Customer A
Concentration Risk [Line Items]
Concentration risk, percentage			12.00%		14.00%
Trade and Other Receivables \| Customer Concentration Risk \| Customer B
Concentration Risk [Line Items]
Concentration risk, percentage			45.00%		23.00%

Description of the Business and Summary of Significant Accounting Policies - Non-trade Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Non-trade receivables	$ 14.0	$ 46.2

Description of the Business and Summary of Significant Accounting Policies - Deferred Commissions, Net (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Capitalized Contract Cost [Line Items]
Additional contract costs deferred	$ 7,400,000	$ 7,400,000	$ 21,100,000	$ 24,900,000
Deferred contract costs, amortization period	5 years		5 years
Amortization of deferred commissions	$ 4,600,000	$ 3,200,000	$ 12,700,000	$ 8,500,000
Impairment loss related to deferred costs			0
Deferred Commissions \| Prepaid Expenses and Other Current Assets
Capitalized Contract Cost [Line Items]
Deferred contract costs	18,700,000		18,700,000		$ 14,500,000
Deferred Commissions \| Other Assets
Capitalized Contract Cost [Line Items]
Deferred contract costs	$ 42,500,000		$ 42,500,000		$ 38,300,000

Description of the Business and Summary of Significant Accounting Policies - Property and Equipment, Net (Details)	9 Months Ended
	Sep. 30, 2019
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Minimum \| Datacenter and other computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Minimum \| Office equipment and other
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years
Maximum \| Datacenter and other computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Maximum \| Office equipment and other
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years

Description of the Business and Summary of Significant Accounting Policies - Equity Investments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gain on equity investments	$ (1.7)	$ 5.7	$ 0.0

Description of the Business and Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset	$ 581.7
Operating lease, liability	$ 702.2
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset		$ 431.7
Operating lease, liability		$ 502.4

Cash, Cash Equivalents and Short-Term Investments - Schedule of Components (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 443.2	$ 519.3
Total cash equivalents	443.2	519.3
Short-term investments, amortized cost	586.2	570.5
Short-term investments, unrealized gain	1.7	0.1
Short-term investments, unrealized loss	(0.2)	(0.6)
Short-term investments, estimated fair value	587.7	570.0
Total cash, cash equivalents, and short term investments, before unrealized gains (losses) on investments	1,029.4	1,089.8
Total cash, cash equivalents, and short term investments	1,030.9	1,089.3
Corporate notes and obligations
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	258.5	269.6
Short-term investments, unrealized gain	1.4	0.1
Short-term investments, unrealized loss	0.0	(0.5)
Short-term investments, estimated fair value	259.9	269.2
US Treasury securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	176.1	176.0
Short-term investments, unrealized gain	0.3	0.0
Short-term investments, unrealized loss	(0.1)	(0.1)
Short-term investments, estimated fair value	176.3	175.9
Certificates of deposit
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	44.9	70.6
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	0.0	0.0
Short-term investments, estimated fair value	44.9	70.6
Asset-backed securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	44.8
Short-term investments, unrealized gain	0.0
Short-term investments, unrealized loss	(0.1)
Short-term investments, estimated fair value	44.7
Commercial paper
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	34.4	17.2
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	0.0	0.0
Short-term investments, estimated fair value	34.4	17.2
US Agency securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	25.1	37.1
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	0.0	0.0
Short-term investments, estimated fair value	25.1	37.1
Municipal securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	2.4
Short-term investments, unrealized gain	0.0
Short-term investments, unrealized loss	0.0
Short-term investments, estimated fair value	2.4
Cash
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	102.0	103.0
Total cash equivalents	102.0	103.0
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	333.2	355.5
Total cash equivalents	333.2	355.5
US Treasury securities
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	7.0	33.4
Total cash equivalents	7.0	33.4
Asset-backed securities
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	1.0
Total cash equivalents	$ 1.0
Commercial paper
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		27.4
Total cash equivalents		$ 27.4

Cash, Cash Equivalents and Short-Term Investments - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) investment	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) investment	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Cash and Cash Equivalents [Abstract]
Cash in transit for credit and debit card transactions	$ 16,600,000		$ 16,600,000		$ 11,900,000
Number of investments in unrealized loss positions \| investment	65		65
Other-than-temporary impairment loss			$ 0
Interest income	$ (5,700,000)	$ (5,000,000.0)	$ (17,500,000)	$ (10,800,000)

Cash, Cash Equivalents and Short-Term Investments - Contractual Maturities (Details) $ in Millions	Sep. 30, 2019 USD ($)
Amortized cost
Due within one year	$ 261.5
Due between one to three years	324.7
Total	586.2
Estimated fair value
Due within one year	261.9
Due between one to three years	325.8
Total	$ 587.7

Property and Equipment, Net - Schedule of Components (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 999.8	$ 874.5
Accumulated depreciation and amortization	(583.2)	(563.9)
Property and equipment, net	416.6	310.6
Datacenter and other computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	741.9	667.4
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	34.6	23.8
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	203.6	150.5
Construction in process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 19.7	$ 32.8

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 999.8		$ 999.8		$ 874.5
Accumulated depreciation	583.2		583.2		563.9
Depreciation	37.1	$ 43.3	122.5	$ 115.4
Infrastructure Assets Acquired Under Finance Lease Agreements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	299.1		299.1
Accumulated depreciation	$ 117.6		$ 117.6		211.7
Infrastructure Assets Held under Capital Leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross					$ 362.8

Business Combinations - Schedule of Purchase Consideration (Details) - HelloSign Inc. $ in Millions	Feb. 08, 2019 USD ($)
Business Acquisition [Line Items]
Fair value of assumed HelloSign options attributable to pre-combination services (1)	$ 0.8
Purchase price adjustments	(0.5)
Total purchase consideration	177.9
Preferred Stockholders and Vested Option Holders
Business Acquisition [Line Items]
Cash and transaction costs paid	175.2
HelloSign
Business Acquisition [Line Items]
Cash and transaction costs paid	$ 2.4

Business Combinations - Narrative (Details) - HelloSign Inc. - USD ($) $ in Millions		9 Months Ended
	Feb. 08, 2019	Sep. 30, 2019
Business Acquisition [Line Items]
Purchase consideration, agreements with key personnel	$ 48.5
Acquired finite-lived intangible assets weighted average amortization period	4 years 10 months 24 days
Transaction costs		$ 1.0

Business Combinations - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Sep. 30, 2019	Feb. 08, 2019	Dec. 31, 2018
Liabilities assumed:
Goodwill	$ 231.8		$ 96.5
HelloSign Inc.
Assets acquired:
Cash and cash equivalents		$ 5.5
Short-term investments		7.8
Acquisition-related intangible assets		44.6
Accounts receivable, prepaid and other assets		5.0
Total assets acquired		62.9
Liabilities assumed:
Accounts payable, accrued and other liabilities		6.3
Deferred revenue		4.8
Deferred tax liability		6.9
Total liabilities assumed		18.0
Net assets acquired, excluding goodwill		44.9
Total purchase consideration		177.9
Goodwill		$ 133.0

Business Combinations - Schedule of Assets Acquired (Details) - HelloSign Inc. $ in Millions	Feb. 08, 2019 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair values	$ 44.6
Estimated weighted average useful lives (In years)	4 years 10 months 24 days
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair values	$ 20.5
Estimated weighted average useful lives (In years)	4 years 10 months 24 days
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair values	$ 19.6
Estimated weighted average useful lives (In years)	5 years
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated fair values	$ 4.5
Estimated weighted average useful lives (In years)	5 years

Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 104.2	$ 100.4
Accumulated amortization	(54.1)	(85.7)
Intangible assets, net	50.1	14.7
Developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	25.0	47.0
Intangible assets, retired	$ 41.7
Developed technology \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	4 years 4 months 24 days
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 20.5	0.0
Customer relationships \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	4 years 3 months 18 days
Software
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 20.0	19.2
Software \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	1 year 9 months 18 days
Patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 13.0	13.0
Patents \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	7 years 8 months 12 days
Assembled workforce in asset acquisitions
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 12.6	12.6
Assembled workforce in asset acquisitions \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	1 year 3 months 18 days
Licenses
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 4.6	4.6
Licenses \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	1 year 9 months 18 days
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 5.2	0.7
Trademarks and trade names \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	4 years 4 months 24 days
Other
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 3.3	$ 3.3
Other \| Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted- average remaining useful life (In years)	5 years 9 months 18 days

Intangible Assets - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 3.6	$ 1.5	$ 10.1	$ 4.7
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Remaining three months of Fiscal 2019	3.6		3.6
2020	13.6		13.6
2021	11.3		11.3
2022	8.0		8.0
2023	7.7		7.7
Thereafter	5.9		5.9
Total	$ 50.1		$ 50.1

Goodwill (Details) - USD ($)	9 Months Ended	12 Months Ended
Goodwill (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance	$ 96,500,000
HelloSign acquisition	133,000,000.0
Effect of foreign currency translation	2,300,000
Ending balance	231,800,000	$ 96,500,000
Goodwill impairment	$ 0	$ 0

Revolving Credit Facility (Details) - Credit And Guarantee Agreement - Line of Credit - USD ($)		1 Months Ended
	Apr. 30, 2017	Apr. 30, 2019	Sep. 30, 2019	Feb. 28, 2018
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 600,000,000.0			$ 725,000,000.0
Debt issuance fees	$ 2,600,000			400,000
Debt instrument, term		5 years
Line of credit facility, accordion feature, increase limit				275,000,000.0
Unused capacity, commitment fee (percent)	0.20%
Covenant terms, minimum liquidity balance	$ 100,000,000.0
Aggregate letters of credit outstanding amount			$ 60,000,000.0
Remaining borrowing capacity			$ 665,000,000.0
Revolving Credit Facility \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	1.50%
Revolving Credit Facility \| Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate (percent)	0.50%
Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity				$ 187,500,000
Commitment fee (percent)	1.50%
Fronting fee (percent)	0.125%

Leases - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
Leases - Narrative (Details) - USD ($)	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Lease, renewal term			5 years
Sublease income	$ 1,800,000	$ 2,800,000	$ 5,300,000	$ 9,400,000
Minimum obligations					$ 838,900,000
Tenant improvements					75,000,000.0
Tenant improvement allowance reimbursement			(45,400,000)	$ 0
Operating leases, not yet commenced, value			$ 220,200,000
Minimum
Lessee, Lease, Description [Line Items]
Lease, remaining lease term			1 year
Operating sublease, term			1 year
Operating leases, not yet commenced, term of contract	4 years		4 years
Maximum
Lessee, Lease, Description [Line Items]
Lease, remaining lease term			14 years
Operating sublease, term			4 years
Operating leases, not yet commenced, term of contract	14 years		14 years
Line of Credit \| Letter of Credit \| Corporate Headquarters Lease
Lessee, Lease, Description [Line Items]
Letter of credit					$ 34,200,000

Leases - Components of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Leases [Abstract]
Operating lease cost	$ 27.4	$ 21.4	$ 75.9	$ 64.4
Finance lease cost:
Amortization of assets under finance lease	18.2	21.9	60.4	66.0
Interest	2.3	2.1	6.8	5.9
Total finance lease cost	$ 20.5	$ 24.0	$ 67.2	$ 71.9

Leases - Other Lease Information (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Apr. 30, 2019	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Payments for operating leases included in cash from operating activities		$ 74.6
Payments for finance leases included in cash from operating activities		6.8
Payments for finance leases included in cash from financing activities		71.8
Assets obtained in exchange for lease obligations: operating leases		202.0
Assets obtained in exchange for lease obligations: finance leases		$ 107.0
Weighted average remaining lease term (in years) - operating leases		10 years 9 months 18 days
Weighted average remaining lease term (in years) - finance leases		3 years
Weighted average discount rate - operating leases		4.40%
Weighted average discount rate - finance leases		4.60%
Corporate Headquarters Lease
Lessee, Lease, Description [Line Items]
Assets obtained in exchange for lease obligations: operating leases	$ 159.3

Leases - Future Minimum Lease Payments (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Operating leases
2019 (excluding the nine months ended September 30, 2019)	$ 26.9
2020	107.7
2021	96.5
2022	86.3
2023	69.7
Thereafter	545.6
Total future minimum lease payments	932.7
Less imputed interest	(213.1)
Less tenant improvement receivables	(17.4)
Operating lease, liability	702.2
Finance Lease, Liability, Payment, Due [Abstract]
2019 (excluding the nine months ended September 30, 2019)	22.8
2020	74.3
2021	59.1
2022	45.1
2023	11.6
Thereafter	0.0
Total future minimum lease payments	212.9
Less imputed interest	(14.0)
Less tenant improvement receivables	0.0
Finance lease, liability	198.9
Rent payments from sub-tenants	$ 38.3
Minimum
Finance Lease, Liability, Payment, Due [Abstract]
Rent payments from sub-tenants, term	1 year
Maximum
Finance Lease, Liability, Payment, Due [Abstract]
Rent payments from sub-tenants, term	4 years

Accrued and Other Current Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Non-income taxes payable	$ 88.3	$ 75.7
Accrued legal and other external fees	28.9	28.1
Deferred rent	0.0	41.0
Other accrued and current liabilities	32.7	19.7
Total accrued and other current liabilities	$ 149.9	$ 164.5

Stockholders' Equity - Common Stock, Convertible Preferred Stock, Preferred Stock (Details)		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 26, 2018 shares	Dec. 31, 2017 shares	Sep. 30, 2019 $ / shares shares	Sep. 30, 2018 shares	Sep. 30, 2019 vote $ / shares shares	Sep. 30, 2018 shares	Dec. 31, 2018 shares
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)			240,000,000.0		240,000,000.0
Restricted Stock
Class of Stock [Line Items]
Shares granted (in shares)					17,900,000
Co-Founder Grants \| Restricted Stock
Class of Stock [Line Items]
Shares granted (in shares)		14,700,000			14,700,000		14,700,000
Class A common stock
Class of Stock [Line Items]
Votes per share \| vote					1
Common stock, shares authorized (in shares)			2,400,000,000.0		2,400,000,000.0
Common stock, par value (in dollars per share) \| $ / shares			$ 0.00001		$ 0.00001
Common stock, shares issued (in shares)			253,900,000		253,900,000		211,000,000.0
Common stock, shares outstanding (in shares)			253,900,000		253,900,000		211,000,000
Class B common stock
Class of Stock [Line Items]
Votes per share \| vote					10
Shares converted in conversion (in shares)			700,000	61,300,000	38,400,000	61,300,000
Common stock, shares authorized (in shares)			475,000,000.0		475,000,000.0
Common stock, par value (in dollars per share) \| $ / shares			$ 0.00001		$ 0.00001
Common stock, shares issued (in shares)			161,400,000		161,400,000		198,600,000
Common stock, shares outstanding (in shares)			161,400,000		161,400,000		198,600,000
Class C common stock
Class of Stock [Line Items]
Votes per share \| vote					0
Common stock, shares authorized (in shares)			800,000,000.0		800,000,000.0
Common stock, par value (in dollars per share) \| $ / shares			$ 0.00001		$ 0.00001
Common stock, shares issued (in shares)			0		0		0
Common stock, shares outstanding (in shares)			0		0		0
Convertible preferred stock \| Conversion of Convertible Preferred Stock to Class B Common Stock
Class of Stock [Line Items]
Shares converted in conversion (in shares)	147,310,563
Convertible preferred stock \| Conversion of Convertible Preferred Stock to Class A Common Stock
Class of Stock [Line Items]
Shares converted in conversion (in shares)	258,620

Stockholders' Equity - Equity Incentive Plans (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)			0.2
Shares issued and outstanding (in shares)	1.9		1.9		1.3
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of equity instruments other than options	$ 52.6	$ 92.0	$ 184.0	$ 847.1
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period			10 years
Remaining unamortized stock-based compensation	$ 583.6		$ 583.6
Unamortized stock-based compensation, requisite service period			2 years 10 months 24 days
2018 Plan \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period			10 years
Vesting period			4 years
2008 Equity Incentive Plan, 2017 Equity Incentive Plan, and 2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued and outstanding (in shares)	31.3		31.3
Shares available for grant (in shares)	69.4		69.4

Stockholders' Equity - Schedule of Stock Option and Restricted Stock Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2019	Dec. 31, 2018
Number of shares available for issuance under the Plans
Beginning balance (in shares)	57.1
Additional shares authorized (in shares)	21.2
Stock options assumed (in shares)	0.9
Options and RSUs canceled (in shares)	5.2
Shares repurchased for tax withholdings on release of restricted stock (unaudited) (in shares)	3.1
Restricted stock granted (in shares)	(18.1)
Ending balance (in shares)	69.4	57.1
Options Outstanding, Number of shares outstanding under the Plans
Beginning balance (in shares)	1.3
Stock options assumed (in shares)	0.9
Options exercised (in shares)	(0.3)
Options canceled (in shares)	(0.2)
Options granted (in shares)	0.2
Ending balance (in shares)	1.9	1.3
Vested during period (in shares)	1.2
Unvested at end of period (in shares)			0.7
Options Outstanding, Weighted- average exercise price per share
Beginning balance (in dollars per share)	$ 14.68
Stock options assumed (in dollars per share)	6.02
Options exercised (in dollars per share)	7.07
Options canceled (in dollars per share)	19.16
Options granted (in dollars per share)	22.63
Ending balance (in dollars per share)	12.26	$ 14.68
Vested during period (in dollars per share)	$ 16.05
Unvested at end of period (in dollars per shares)			$ 6.15
Options Outstanding, Weighted- average remaining contractual term (In years)
Weighted-average contractual term	6 years 9 months 18 days	5 years
Vested during period	5 years 7 months 6 days
Options outstanding, aggregate intrinsic value			$ 17.6	$ 9.1
Vested during period, aggregate intrinsic value			7.0
Unvested during period, aggregate intrinsic value			$ 10.6
Restricted Stock
Restricted Stock Outstanding, Number of Plan shares outstanding
Beginning balance (in shares)	25.0
RSUs released (in shares)	(8.5)
RSUs canceled (in shares)	(5.0)
Restricted stock granted (in shares)	17.9
Ending balance (in shares)	29.4	25.0
Vested during period (in shares)	0.0
Unvested at end of period (in shares)	25.0	25.0	29.4	25.0
Restricted Stock Outstanding, Weighted- average grant date fair value per share
Beginning balance (in dollars per share)	$ 18.68
RSUs released (in dollars per share)	18.90
RSUs canceled (in dollars per share)	18.78
Shares repurchased for tax withholdings on release of restricted stock (in dollars per share)	18.87
Restricted stock granted (in dollars per share)	22.03
Ending balance (in dollars per share)	20.64	$ 18.68
Vested during period (in dollars per share)	0
Unvested at end of period (in dollars per share)	$ 18.68	$ 18.68	$ 20.64	$ 18.68

Stockholders' Equity - Schedule of Pre-Tax Intrinsic Value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stockholders' Equity Note [Abstract]
Intrinsic value of options exercised	$ 0.3	$ 32.0	$ 4.8	$ 34.0

Stockholders' Equity - Assumed Stock Options (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		9 Months Ended
	Feb. 08, 2019	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options assumed (in shares)		0.9
Dividend yield		0.00%
Weighted average grant date fair value of stock options assumed (in dollars per share)		$ 21.60
Fair value of options assumed in business combination		$ 19.4
Post combination, stock-based compensation expense		$ 18.6
HelloSign Inc.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options assumed (in shares)	0.9

Stockholders' Equity - Fair Value of Stock Option Assumptions Used (Details)	9 Months Ended
	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	51.60%
Risk-free interest rate, minimum	2.42%
Risk-free interest rate, maximum	2.51%
Dividend yield	0.00%
Employee Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	3 years 4 months 24 days
Employee Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	7 years

Stockholders' Equity - Co-Founder Grants and Award Modifications (Details) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($) tranche $ / shares shares	Sep. 30, 2019 USD ($) $ / shares	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Dec. 31, 2018 shares	Dec. 31, 2017 USD ($) tranche $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share) \| $ / shares		$ 6.15			$ 6.15
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)					17.9
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock based compensation \| $				$ 10.0
Co-Founder Grants \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	14.7				14.7		14.7
Expiration period	10 years
Number of tranches \| tranche	9							9
Weighted average grant date fair value (in dollars per share) \| $ / shares	$ 10.60							$ 10.60
Unamortized stock-based compensation, requisite service period								5 years 2 months 12 days
Stock-based compensation related to the Co-Founder Grants \| $		$ 8.8	$ 8.8		$ 26.1	$ 28.1
Remaining unamortized stock-based compensation \| $	$ 156.2	$ 93.1			$ 93.1			$ 156.2
Co-Founder Grants \| Restricted Stock \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized stock-based compensation, requisite service period								2 years 10 months 24 days
Co-Founder Grants \| Restricted Stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized stock-based compensation, requisite service period								6 years 10 months 24 days
Co-Founder Grants \| Restricted Stock \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Co-Founder Grants \| Restricted Stock \| Tranche One \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage vested maximum	20.00%
Co-Founder Grants \| Chief Executive Officer \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	10.3
Co-Founder Grants \| Director \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	4.4

Net Loss Per Share - Schedule of EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Net loss attributable to common stockholders	$ (17.0)	$ (5.8)	$ (46.1)	$ (475.4)
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share (in shares)	414.4	403.9	412.4	342.0
Net loss per common share, basic and diluted (in dollars per share)	$ (0.04)	$ (0.01)	$ (0.11)	$ (1.39)
Class A
Class of Stock [Line Items]
Net loss attributable to common stockholders	$ (10.4)	$ (1.9)	$ (26.1)	$ (105.5)
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share (in shares)	252.7	133.2	233.1	75.9
Net loss per common share, basic and diluted (in dollars per share)	$ (0.04)	$ (0.01)	$ (0.11)	$ (1.39)
Class B
Class of Stock [Line Items]
Net loss attributable to common stockholders	$ (6.6)	$ (3.9)	$ (20.0)	$ (369.9)
Weighted-average number of common shares outstanding used in computing basic and diluted net loss per common share (in shares)	161.7	270.7	179.3	266.1
Net loss per common share, basic and diluted (in dollars per share)	$ (0.04)	$ (0.01)	$ (0.11)	$ (1.39)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Loss Per Share - Schedule of Potentially Dilutive Securities Excluded from Computation (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	46.7	47.7	45.3	57.5
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	30.1	28.7	28.7	38.0
Options to purchase shares of common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1.9	4.3	1.9	4.7
Co-Founder Grants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	14.7	14.7	14.7	14.7
Shares subject to repurchase from early-exercised options and unvested restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0.0	0.0	0.0	0.1

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ 1.6	$ (0.2)	$ (3.5)	$ 2.7
Increase in unrecognized tax benefits			9.6
Unrecognized tax benefits that would impact effective tax rate			1.5
HelloSign Inc.
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)			(6.9)
Deferred tax liability	$ 6.9		$ 6.9

Related Party Transactions (Details) - Controlling Shareholders - Dropbox Charitable Foundation	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2016 shareholder
Related Party Transaction [Line Items]
Number of controlling shareholders in related party transaction \| shareholder					2
Payments to related party \| $	$ 0	$ 0	$ 0	$ 0

Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Geographic Areas (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Property and equipment, net	$ 416.6		$ 416.6		$ 310.6
Revenue	428.2	$ 360.3	1,215.3	$ 1,015.8
United States
Segment Reporting Information [Line Items]
Property and equipment, net	403.0		403.0		293.6
Revenue	220.8	182.6	623.4	516.5
International
Segment Reporting Information [Line Items]
Property and equipment, net	13.6		13.6		$ 17.0
Revenue	$ 207.4	$ 177.7	$ 591.9	$ 499.3

Label	Element	Value
Accounting Standards Update 2016-02 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,000,000.0
Accounting Standards Update 2016-02 [Member] \| Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,000,000.0

Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	$ 443.2	$ 519.3
Total short-term investments	587.7	570.0
Corporate notes and obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	259.9	269.2
US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	176.3	175.9
Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	44.9	70.6
Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	44.7
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	34.4	17.2
US Agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	25.1	37.1
Municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	2.4
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	333.2	355.5
US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	7.0	33.4
Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	1.0
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents		27.4
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	587.7	570.0
Total cash equivalents and short-term investments		986.3
Equity investments	10.7
Total	939.6
Fair Value, Measurements, Recurring \| Corporate notes and obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	259.9	269.2
Fair Value, Measurements, Recurring \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	176.3	175.9
Fair Value, Measurements, Recurring \| Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	44.9	70.6
Fair Value, Measurements, Recurring \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	44.7
Fair Value, Measurements, Recurring \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	34.4	17.2
Fair Value, Measurements, Recurring \| US Agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	25.1	37.1
Fair Value, Measurements, Recurring \| Municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	2.4
Fair Value, Measurements, Recurring \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	333.2	355.5
Fair Value, Measurements, Recurring \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	7.0	33.4
Fair Value, Measurements, Recurring \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	1.0
Fair Value, Measurements, Recurring \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents		27.4
Fair Value, Measurements, Recurring \| Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	341.2	416.3
Fair Value, Measurements, Recurring \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Total cash equivalents and short-term investments		355.5
Equity investments	10.7
Total	343.9
Fair Value, Measurements, Recurring \| Level 1 \| Corporate notes and obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 1 \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 1 \| US Agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	333.2	355.5
Fair Value, Measurements, Recurring \| Level 1 \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	0.0
Fair Value, Measurements, Recurring \| Level 1 \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents		0.0
Fair Value, Measurements, Recurring \| Level 1 \| Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	333.2	355.5
Fair Value, Measurements, Recurring \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	587.7	570.0
Total cash equivalents and short-term investments		630.8
Equity investments	0.0
Total	595.7
Fair Value, Measurements, Recurring \| Level 2 \| Corporate notes and obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	259.9	269.2
Fair Value, Measurements, Recurring \| Level 2 \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	176.3	175.9
Fair Value, Measurements, Recurring \| Level 2 \| Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	44.9	70.6
Fair Value, Measurements, Recurring \| Level 2 \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	44.7
Fair Value, Measurements, Recurring \| Level 2 \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	34.4	17.2
Fair Value, Measurements, Recurring \| Level 2 \| US Agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	25.1	37.1
Fair Value, Measurements, Recurring \| Level 2 \| Municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	2.4
Fair Value, Measurements, Recurring \| Level 2 \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring \| Level 2 \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	7.0	33.4
Fair Value, Measurements, Recurring \| Level 2 \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	1.0
Fair Value, Measurements, Recurring \| Level 2 \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents		27.4
Fair Value, Measurements, Recurring \| Level 2 \| Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	8.0	60.8
Fair Value, Measurements, Recurring \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Total cash equivalents and short-term investments		0.0
Equity investments	0.0
Total	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Corporate notes and obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Certificates of deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| US Agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total short-term investments	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| US Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	0.0	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	0.0
Fair Value, Measurements, Recurring \| Level 3 \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents		0.0
Fair Value, Measurements, Recurring \| Level 3 \| Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash equivalents	$ 0.0	$ 0.0