Pinterest (PINS) 10-Q 17 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 10, 2019
Document Information [Abstract]
Entity Registrant Name	Pinterest, Inc.
Entity Central Index Key	0001506293
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	false
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		86,250,000
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		456,286,871

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 134,648	$ 122,509
Marketable securities	507,568	505,304
Accounts receivable net of allowances of $2,600 and $3,097 as of March 31, 2019 and December 31, 2018, respectively	161,108	221,932
Prepaid expenses and other current assets	43,623	39,607
Total current assets	846,947	889,352
Property and equipment, net	83,031	81,512
Operating lease right-of-use assets	160,802	145,203
Goodwill and intangible assets, net	13,728	14,071
Restricted cash	25,724	11,724
Other assets	11,008	10,869
Total assets	1,141,240	1,152,731
Current liabilities:
Accounts payable	30,320	22,169
Accrued expenses and other current liabilities	93,206	86,258
Operating lease liabilities	123,526	108,427
Operating lease liabilities	162,359	151,395
Other liabilities	23,945	22,073
Total liabilities	309,830	281,895
Commitments and contingencies
Redeemable convertible preferred stock, $0.00001 par value, 928,676 shares authorized; 308,373 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	1,465,399	1,465,399
Stockholders’ equity (deficit):
Common stock, $0.00001 par value, 1,932,500 shares authorized; 127,371 and 127,298 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	253,016	252,212
Accumulated other comprehensive loss	(231)	(1,421)
Accumulated deficit	(886,775)	(845,355)
Total stockholders’ equity (deficit)	(633,989)	(594,563)
Total liabilities, redeemable convertible preferred stock, and stockholders’ equity (deficit)	$ 1,141,240	$ 1,152,731

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowances	$ 2,600	$ 3,097
Redeemable convertible preferred stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Redeemable convertible preferred stock, Shares authorized (in shares)	928,676,000	928,676,000
Redeemable convertible preferred stock, Shares issued (in shares)	308,373,000	308,373,000
Redeemable convertible preferred stock, Shares outstanding (in shares)	308,373,000	308,373,000
Common Stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Common Stock, Shares authorized (in shares)	1,932,500,000	1,932,500,000
Common Stock, Shares issued (in shares)	127,371,000	127,298,000
Common Stock, Shares outstanding (in shares)	127,371,000	127,298,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenue	$ 201,911	$ 131,359
Costs and expenses:
Cost of revenue	73,694	51,653
Research and development	72,444	60,047
Sales and marketing	76,394	55,774
General and administrative	24,205	18,867
Total costs and expenses	246,737	186,341
Loss from operations	(44,826)	(54,982)
Other income (expense), net:
Interest income	4,059	2,638
Interest expense and other income (expense), net	(500)	(242)
Loss before provision for income taxes	(41,267)	(52,586)
Provision for income taxes	153	123
Net loss	$ (41,420)	$ (52,709)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.33)	$ (0.42)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	127,346	126,857

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (41,420)	$ (52,709)
Other comprehensive income, net of taxes:
Change in unrealized gain (loss) on available-for-sale marketable securities	1,189	(1,127)
Change in foreign currency translation adjustment	1	68
Comprehensive loss	$ (40,230)	$ (53,768)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance, shares (in shares) at Dec. 31, 2017	308,373,000
Beginning balance at Dec. 31, 2017	$ 1,465,399
Ending balance, shares (in shares) at Mar. 31, 2018	308,373,000
Ending balance at Mar. 31, 2018	$ 1,465,399
Beginning balance (in shares) at Dec. 31, 2017		126,771,000
Beginning balance at Dec. 31, 2017	(546,464)	$ 1	$ 236,682	$ (766)	$ (782,381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash upon exercise of stock options, net (in shares)		140,000
Issuance of common stock for cash upon exercise of stock options, net	435		435
Share-based compensation expense	4,834		4,834
Other comprehensive loss	(1,059)			(1,059)
Net loss attributable to common stockholders	(52,709)				(52,709)
Ending balance (in shares) at Mar. 31, 2018		126,911,000
Ending balance at Mar. 31, 2018	$ (594,963)	$ 1	241,951	(1,825)	(835,090)
Beginning balance, shares (in shares) at Dec. 31, 2018	308,373,000
Beginning balance at Dec. 31, 2018	$ 1,465,399
Ending balance, shares (in shares) at Mar. 31, 2019	308,373,000
Ending balance at Mar. 31, 2019	$ 1,465,399
Beginning balance (in shares) at Dec. 31, 2018		127,298,000
Beginning balance at Dec. 31, 2018	$ (594,563)	$ 1	252,212	(1,421)	(845,355)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash upon exercise of stock options, net (in shares)	73,000	73,000
Issuance of common stock for cash upon exercise of stock options, net	$ 110		110
Share-based compensation expense	694		694
Other comprehensive loss	1,190			1,190
Net loss attributable to common stockholders	(41,420)				(41,420)
Ending balance (in shares) at Mar. 31, 2019		127,371,000
Ending balance at Mar. 31, 2019	$ (633,989)	$ 1	$ 253,016	$ (231)	$ (886,775)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net loss	$ (41,420)	$ (52,709)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5,696	4,787
Share-based compensation	694	4,834
Other	(993)	654
Changes in assets and liabilities:
Accounts receivable	61,329	39,309
Prepaid expenses and other assets	510	7,102
Operating lease right-of-use assets	6,427	4,551
Accounts payable	7,481	4,484
Accrued expenses and other liabilities	(2,024)	2,696
Operating lease liabilities	(4,578)	(2,174)
Net cash provided by operating activities	33,122	13,534
Investing activities
Purchases of property and equipment	(3,706)	(8,240)
Purchases of marketable securities	(113,952)	(83,569)
Sales of marketable securities	28,953	36,408
Maturities of marketable securities	84,883	142,428
Net cash provided by (used in) investing activities	(3,822)	87,027
Financing activities
Proceeds from exercise of stock options, net	110	435
Other financing activities	(3,279)	0
Net cash provided by (used in) financing activities	(3,169)	435
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	8	48
Net increase in cash, cash equivalents, and restricted cash	26,139	101,044
Cash, cash equivalents, and restricted cash, beginning of period	135,290	83,969
Cash, cash equivalents, and restricted cash, end of period	$ 161,429	$ 185,013

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - Supplemental Information - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental cash flow information
Accrued property and equipment	$ 4,484	$ 7,779
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	22,862	2,356
Reconciliation of cash, cash equivalents and restricted cash to condensed consolidated balance sheets
Cash and cash equivalents	134,648	172,512
Restricted cash included in prepaid expenses and other current assets	1,057	851
Restricted cash	25,724	11,650
Total cash, cash equivalents, and restricted cash	$ 161,429	$ 185,013

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Description of Business Pinterest was incorporated in Delaware in 2008 and is headquartered in San Francisco, California. Pinterest is a visual discovery engine that people around the globe use to find the inspiration to create a life they love. We generate revenue by delivering advertising on our website and mobile application. Basis of Presentation and Consolidation We prepared the accompanying condensed consolidated financial statements in accordance with generally accepted accounting principles in the United States ("GAAP"). The condensed consolidated financial statements include the accounts of Pinterest, Inc. and its wholly owned subsidiaries. We have eliminated all intercompany balances and transactions. The condensed consolidated balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. We have condensed or omitted certain information and notes normally included in complete financial statements prepared in accordance with GAAP. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2018 , which are included in our prospectus filed pursuant to Rule 424(b) on April 18, 2019. In our opinion, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but they are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2019 . Initial Public Offering On April 23, 2019, we closed our initial public offering ("IPO") in which we issued and sold 75,000,000 shares of Class A common stock at $19.00 per share. We received net proceeds of $1,368.0 million after deducting underwriting discounts and commissions and before deducting estimated offering costs of $8.7 million , of which $5.6 million was included in other assets as of March 31, 2019 . Immediately prior to the completion of our IPO, all shares of our outstanding redeemable convertible preferred stock and redeemable convertible preferred stock warrants converted into 308,621,636 shares of Class B common stock on a one -for-one basis, and immediately thereafter but still prior to the completion of our IPO, all of our outstanding common stock were reclassified into 456,213,756 shares of Class B common stock on a one -for-one basis. On April 29, 2019, we issued and sold an additional 11,250,000 shares of Class A common stock at $19.00 per share pursuant to the underwriters’ option to purchase additional shares. We received additional net proceeds of $205.2 million after deducting underwriting discounts and commissions. The shares and proceeds from our IPO and the underwriters’ exercise of their option to purchase additional shares are not reflected in the condensed consolidated financial statements as of and for the three months ended March 31, 2019 . Stock Split On March 28, 2019, we effected a 1-for-3 reverse split of our capital stock. We have adjusted all share and per share amounts in the accompanying condensed consolidated financial statements and notes to reflect the reverse stock split. Use of Estimates Preparing our condensed consolidated financial statements in conformity with GAAP requires us to make estimates and judgments that affect amounts reported in the condensed consolidated financial statements and accompanying notes. We base these estimates and judgments on historical experience and various other assumptions that we consider reasonable. GAAP requires us to make estimates and assumptions in several areas, including the fair values of financial instruments, assets acquired and liabilities assumed through business combinations, common stock prior to our IPO and share-based awards, and contingencies as well as the collectability of our accounts receivable, the useful lives of our intangible assets and property and equipment, the incremental borrowing rate we use to determine our operating lease liabilities, and revenue recognition, among others. Actual results could differ materially from these estimates and judgments. Segments We operate as a single operating segment. Our chief operating decision maker is our Chief Executive Officer, who reviews financial information presented on a consolidated basis, accompanied by disaggregated information about our revenue, for purposes of making operating decisions, assessing financial performance and allocating resources. Revenue Recognition We generate revenue by delivering ads on our website and mobile application. We recognize revenue only after transferring control of promised goods or services to customers, which occurs when a user clicks on an ad contracted on a cost per click (“CPC”) basis or views an ad contracted on a cost per thousand impressions (“CPM”) basis. We typically bill customers on a CPC or CPM basis, and our payment terms vary by customer type and location. The term between billing and payment due dates is not significant. We occasionally offer customers free ad inventory or measurement studies that demonstrate the effectiveness of their advertising campaigns on our platform. In either case, we recognize revenue only after satisfying our contractual performance obligation. When contracts with our customers contain multiple performance obligations, we allocate the overall transaction price, which is the amount of consideration to which we expect to be entitled in exchange for promised goods or services, to each of the distinct performance obligations based on their relative standalone selling prices. We generally determine standalone selling prices based on the effective price charged per contracted click or impression or based on expected cost plus margin, and we do not disclose the value of unsatisfied performance obligations because the original expected duration of our contracts is generally less than one year. We record sales commissions in sales and marketing expense as incurred because we would amortize these over a period of less than one year. Deferred revenue was not material as of March 31, 2019 and December 31, 2018 . Share-Based Compensation We have granted restricted stock units ("RSUs") since March 2015. We measure RSUs based on the fair market value of our common stock on the grant date. RSUs granted under our 2009 Stock Plan (the "2009 Plan") are subject to both a service condition, which is typically satisfied over four years , and a performance condition, which was deemed satisfied upon the pricing of the shares of Class A common stock sold in connection with our IPO. Because the performance condition had not been satisfied as of March 31, 2019 , we had not recorded any share-based compensation expense for our RSUs at that date. Had our IPO occurred on March 31, 2019, we would have recorded cumulative share-based compensation expense using the accelerated attribution method for those RSUs for which the service condition had been satisfied at that date and would have begun recording the remaining unrecognized share-based compensation expense over the remainder of the requisite service period. We account for forfeitures as they occur. Valuation of Common Stock and Redeemable Convertible Preferred Stock Warrants Until our IPO, we determined the fair value of our common stock and redeemable convertible preferred stock warrants using the most observable inputs available to us, including recent sales of our stock as well as income and market valuation approaches. The income approach estimates the value of our business based on the future cash flows we expect to generate discounted to their present value using an appropriate discount rate to reflect the risk of achieving the expected cash flows. The market approach estimates the value of our business by applying valuation multiples derived from the observed valuation multiples of comparable public companies to our expected financial results. We used the Probability Weighted Expected Return Method ("PWERM") to allocate the value of our business among our outstanding stock and share-based awards. We applied the PWERM by first defining the range of potential future liquidity outcomes for our business, such as an IPO, and then allocating its value to our outstanding stock and share-based awards based on the relative probability that each outcome will occur. We used the Option Pricing Method to allocate the value of our business to our outstanding stock and share-based awards under the non-IPO outcome we considered within the PWERM. Applying these valuation and allocation approaches involved the use of estimates, judgments, and assumptions that are highly complex and subjective, such as those regarding our expected future revenue, expenses, and cash flows, discount rates, valuation multiples, the selection of comparable public companies, and the probability of future events. Changes in any or all of these estimates and assumptions, or the relationships between these assumptions, impacted our valuation as of each valuation date and may have a material impact on the valuation of our common stock and redeemable convertible preferred stock warrants. Following our IPO, there is an active market for our Class A common stock and the warrants to purchase shares of our redeemable convertible preferred stock are no longer outstanding, so we no longer apply these valuation and allocation approaches. Leases and Operating Lease Incremental Borrowing Rate We lease office space under operating leases with expiration dates through 2033 . We determine whether an arrangement constitutes a lease and record lease liabilities and right-of-use assets on our condensed consolidated balance sheets at lease commencement. We measure lease liabilities based on the present value of the total lease payments not yet paid discounted based on the more readily determinable of the rate implicit in the lease or our incremental borrowing rate, which is the estimated rate we would be required to pay for a collateralized borrowing equal to the total lease payments over the term of the lease. We estimate our incremental borrowing rate based on an analysis of publicly traded debt securities of companies with credit and financial profiles similar to our own. We measure right-of-use assets based on the corresponding lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs we incur and (iii) tenant incentives under the lease. We begin recognizing rent expense when the lessor makes the underlying asset available to us, we do not assume renewals or early terminations unless we are reasonably certain to exercise these options at commencement, and we do not allocate consideration between lease and non-lease components. For short-term leases, we record rent expense in our condensed consolidated statements of operations on a straight-line basis over the lease term and record variable lease payments as incurred.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair values of the financial instruments we measure at fair value on a recurring basis are as follows (in thousands): March 31, 2019 Level 1 Level 2 Level 3 Total Cash equivalents: Commercial paper $ — $ 76,897 $ — $ 76,897 Money market funds 546 — — 546 Marketable securities: Corporate bonds — 214,819 — 214,819 Asset-backed securities — 108,059 — 108,059 Certificates of deposit — 64,418 — 64,418 Commercial paper — 100,212 — 100,212 U.S. treasury securities 20,060 — — 20,060 Prepaid expenses and other current assets: Certificates of deposit — 1,057 — 1,057 Restricted cash: Certificates of deposit — 25,724 — 25,724 Other liabilities: Redeemable convertible preferred stock warrants $ — $ — $ 5,005 $ 5,005 December 31, 2018 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 785 $ — $ — $ 785 Commercial paper — 73,486 — 73,486 Marketable securities: Corporate bonds — 204,170 — 204,170 U.S. treasury securities 35,921 — — 35,921 Asset-backed securities — 106,658 — 106,658 Certificates of deposit — 68,359 — 68,359 Commercial paper — 90,196 — 90,196 Prepaid expenses and other current assets: Certificates of deposit — 1,057 — 1,057 Restricted cash: Certificates of deposit — 11,724 — 11,724 Other liabilities: Redeemable convertible preferred stock warrants $ — $ — $ 4,934 $ 4,934 We classify our marketable securities within Level 1 or Level 2 because we determine their fair values using quoted market prices or alternative pricing sources and models utilizing market observable inputs. We classify our redeemable convertible preferred stock warrants within Level 3 because we determine their fair values using significant unobservable inputs, including the fair value of our redeemable convertible preferred stock, which we determine in the same manner as our common stock. Refer to our significant accounting policies in Note 1 for additional information. We record changes in the fair value of our redeemable convertible preferred stock warrants in interest expense and other income (expense), net. These amounts were not material for the three months ended March 31, 2019 and 2018 . Gross unrealized gains and losses on our marketable securities were immaterial in the aggregate as of March 31, 2019 and December 31, 2018 , and gross unrealized losses for marketable securities that had been in an unrealized loss position for greater than 12 consecutive months were also immaterial as of March 31, 2019 and December 31, 2018 . We evaluated all available evidence and concluded that our marketable securities are not other than temporarily impaired as of March 31, 2019 and December 31, 2018 . The fair value of our marketable securities by contractual maturity is as follows (in thousands): March 31, 2019 Due in one year or less $ 319,271 Due after one to five years 188,297 Total $ 507,568 Net realized gains and losses from sales of available-for-sale securities were not material for any period presented.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments In March 2019, we entered into a lease for approximately 490,000 square feet of office space to be constructed near our current headquarters campus in San Francisco, California. The estimated commencement and expiration dates are in 2022 and 2033 , respectively. We may terminate the lease prior to commencement if certain contingencies are not satisfied. We will be subject to total noncancelable minimum lease payments of approximately $420.0 million if these contingencies are met, and if the lease commences we will record a right-of-use asset and related lease liability of no more than that amount at lease commencement using our incremental borrowing rate at that date. Legal Matters We are involved in various lawsuits, claims and proceedings that arise in the ordinary course of business. While the results of legal matters are inherently uncertain, we do not believe the ultimate resolution of these matters, either individually or in aggregate, will have a material adverse effect on our business, financial position, results of operations or cash flows. Letters of Credit We had $24.6 million and $10.6 million of secured letters of credit outstanding as of March 31, 2019 and December 31, 2018 , respectively. These primarily relate to our office space leases and are fully collateralized by certificates of deposit which we record in prepaid expenses and other current assets or restricted cash in our condensed consolidated balance sheets based on the term of the remaining restriction.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation Equity Incentive Plan In June 2009, our board of directors adopted and approved our 2009 Plan, which provides for the issuance of stock options, restricted stock and RSUs to qualified employees, directors and consultants. Stock options granted under our 2009 Stock Plan have a maximum life of 10 years and an exercise price not less than 100% of the fair market value of our common stock on the date of grant. RSUs granted under our 2009 Plan have a maximum life of seven years . 22,641,049 shares of our common stock were reserved for future issuance under our 2009 Plan as of March 31, 2019 . In connection with the closing of our IPO, all remaining shares available for future issuance under our 2009 Plan ceased to be available for issuance under our 2009 Plan, and an equal number of shares of our Class A common stock became available for issuance under our 2019 Omnibus Incentive Plan (the “2019 Plan”), as described below. Our 2019 Plan became effective upon closing of our IPO and succeeds our 2009 Plan. Our 2019 Plan provides for the issuance of stock options, restricted stock, RSUs and other equity- or cash-based awards to qualified employees, directors and consultants. We initially reserved 48,200,000 shares of our Class A common stock for issuance under the 2019 Plan. There are 86,807,385 shares of our Class B common stock reserved for future issuance under our 2019 Plan following the closing of our IPO, which includes the 48,200,000 shares of Class A common stock originally reserved, the 22,641,049 shares of our Class B common stock reserved for future issuance under our 2009 Plan as of March 31, 2019 and 15,966,336 shares of our Class B common stock we withheld to satisfy our tax withholding and remittance obligations related to RSUs for which the performance condition was deemed satisfied upon pricing of our shares of Class A common stock sold in connection with our IPO. The withheld shares were automatically retired and cancelled, and an equal number of shares of our Class A common stock became available for issuance under our 2019 Plan. The number of shares of our Class A common stock available for issuance under the 2019 Plan will be further increased by the number of shares of our Class B common stock subject to awards outstanding under our 2009 Plan as of the closing of our IPO that would, but for the terms of the 2019 Plan, have returned to the share reserves of the 2009 Plan pursuant to the terms of such awards, including as the result of forfeiture, repurchase, expiration or retention by us in order to satisfy an award’s exercise price or tax withholding obligations. In addition, the number of shares of our Class A common stock reserved for issuance under our 2019 Plan will automatically increase on the first day of each fiscal year, commencing on January 1, 2020 and ending on (and including) January 1, 2029, in an amount equal to 5% of the total number of shares of our Class A common stock and our Class B common stock outstanding on the last day of the calendar month before the date of each automatic increase, or a lesser number of shares determined by our board of directors. Stock Option Activity Stock option activity during the three months ended March 31, 2019 , was as follows (in thousands, except per share amounts): Stock Options Outstanding Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (1) (in years) Outstanding as of December 31, 2018 76,635 $ 2.22 4.5 $ 1,285,338 Exercised (73) 2.58 Forfeited (6) 3.84 Outstanding as of March 31, 2019 76,556 $ 2.22 4.3 $ 1,339,176 Exercisable as of March 31, 2019 76,351 $ 2.21 4.3 $ 1,335,964 (1) We calculate intrinsic value based on the difference between the exercise price of in-the-money-stock options and the fair value of our common stock as of the respective balance sheet date. The total grant-date fair value of stock options vested during the three months ended March 31, 2019 and 2018 , was $0.6 million and $18.6 million , respectively. The aggregate intrinsic value of stock options exercised during the three months ended March 31, 2019 and 2018 , was $1.2 million and $5.9 million , respectively. Restricted Stock Unit Activity RSU activity during the three months ended March 31, 2019 , was as follows (in thousands, except per share amounts): Restricted Stock Units Outstanding Shares Weighted Average Grant Date Fair Value Outstanding as of December 31, 2018 77,882 $ 17.79 Granted 28,531 19.60 Forfeited (2,486) 18.43 Outstanding as of March 31, 2019 103,927 $ 18.27 Share-Based Compensation Share-based compensation expense during the three months ended March 31, 2019 and 2018 , was as follows (in thousands): Three Months Ended March 31, 2019 2018 Cost of revenue $ 15 $ 32 Research and development 626 4,054 Sales and marketing 29 241 General and administrative 24 507 Total share-based compensation $ 694 $ 4,834 We began granting RSUs in March 2015. RSUs granted under our 2009 Plan are subject to both a service condition, which is typically satisfied over four years , and a performance condition, which was deemed satisfied in connection with our IPO. Because the performance condition had not been satisfied as of March 31, 2019 , we had not recorded any share-based compensation expense for our RSUs at that date. Had our IPO occurred on March 31, 2019 , we would have recorded cumulative share-based compensation expense of $974.9 million using the accelerated attribution method, and we would have expected to recognize the remaining $924.5 million of unrecognized share-based compensation expense over a weighted-average period of 3.7 years. Unrecognized share-based compensation expense relating to stock options was not material as of March 31, 2019 .

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders We present net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities, and we consider all series of our redeemable convertible preferred stock participating securities. We have not allocated net loss attributable to common stockholders to our redeemable convertible preferred stock because the holders of our redeemable convertible preferred stock are not contractually obligated to share in our losses. We calculate basic net loss per share attributable to common stockholders by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share attributable to common stockholders gives effect to all potential shares of common stock, including common stock issuable upon conversion of our redeemable convertible preferred stock and redeemable convertible preferred stock warrants, stock options, RSUs and common stock warrants to the extent these are dilutive. We calculated basic and diluted net loss per share attributable to common stockholders as follows (in thousands, except per share amounts): Three Months Ended March 31, 2019 2018 Numerator: Net loss attributable to common stockholders $ (41,420 ) $ (52,709 ) Denominator: Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 127,346 126,857 Net loss per share attributable to common stockholders, basic and diluted $ (0.33 ) $ (0.42 ) Basic net loss per share is the same as diluted net loss per share because we reported net losses for all periods presented. We excluded the following weighted-average potential shares of common stock from our calculation of diluted net loss per share attributable to common stockholders because these would be anti-dilutive (in thousands): Three Months Ended March 31, 2019 2018 Redeemable convertible preferred stock 308,373 308,373 Outstanding stock options 76,584 77,341 Unvested restricted stock units 81,498 58,447 Redeemable convertible preferred stock warrants 249 89 Common stock warrants — 167 Total 466,704 444,417

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We determine our income tax provision for interim periods using an estimate of our annual effective tax rate adjusted for discrete items occurring during the periods presented. The primary difference between our effective tax rate and the federal statutory rate is the full valuation allowance we have established on our federal and state net operating losses and credits. Income taxes from international operations are not material for the three months ended March 31, 2019 and 2018 .

Geographical Information

Geographical Information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Geographical Information	Geographical Information Revenue disaggregated by geography based on our customers’ billing addresses is as follows (in thousands): Three Months Ended March 31, 2019 2018 United States $ 181,762 $ 121,382 International (1) 20,149 9,977 Total revenue $ 201,911 $ 131,359 (1) No individual country other than the United States exceeded 10% of our total revenue for any period presented. Property and equipment, net and operating lease right-of-use assets by geography is as follows (in thousands): March 31, December 31, 2019 2018 United States $ 234,794 $ 222,188 International (1) 9,039 4,527 Total property and equipment, net and operating lease right-of-use assets $ 243,833 $ 226,715 (1) No individual country other than the United States exceeded 10% of our total property and equipment, net for any period presented.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Dual Class Structure Immediately prior to the closing of our IPO on April 23, 2019, we filed an amended certificate of incorporation, which created Class A common stock and Class B common stock. All shares of our common stock outstanding immediately prior to the completion of our IPO, including shares of our common stock issued upon conversion of our redeemable convertible preferred stock and redeemable convertible preferred stock warrants and shares of our common stock underlying stock options and RSUs granted under our 2009 Plan, were converted into shares of Class B common stock. The rights of holders of our Class A common stock and Class B common stock are identical, except with respect to voting, conversion and transfer rights. Each share of Class A common stock is entitled to one vote and each share of Class B common stock is entitled to twenty votes. Initial Public Offering On April 23, 2019, we closed our IPO in which we issued and sold 75,000,000 shares of Class A common stock at $19.00 per share. We received net proceeds of $1,368.0 million after deducting underwriting discounts and commissions and before deducting estimated offering costs of $8.7 million , of which $5.6 million was included in other assets as of March 31, 2019 . Immediately prior to the completion of our IPO, all shares of our outstanding redeemable convertible preferred stock and redeemable convertible preferred stock warrants automatically converted into 308,621,636 shares of Class B common stock on a one -for-one basis, and immediately thereafter but still prior to the completion of our IPO all of our outstanding common stock were reclassified into 456,213,756 shares of Class B common stock on a one -for-one basis. On April 29, 2019, we issued and sold an additional 11,250,000 shares of Class A common stock at $19.00 per share pursuant to the underwriters’ option to purchase additional shares. We received additional net proceeds of $205.2 million after deducting underwriting discounts and commissions. The shares and proceeds from our IPO and the underwriters’ exercise of their option to purchase additional shares are not reflected in the condensed consolidated financial statements as of and for the three months ended March 31, 2019 . The pro forma condensed consolidated balance sheet data below reflects the aforementioned conversions as well as: i. An increase to additional paid-in capital related to our receipt of total net proceeds of $1,573.2 million after deducting total underwriting discounts and commissions of $65.6 million and before deducting estimated offering costs of $8.7 million . ii. An increase to additional paid-in capital and accumulated deficit related to the recognition of $974.9 million of share-based compensation expense related to RSUs granted prior to our IPO, which were subject to both a service condition, which is typically satisfied over four years , and a performance condition, which was satisfied upon completion of our IPO. Upon satisfaction of the performance condition, we released 20,221,114 shares of Class B common stock, net, and made cash payments of $303.3 million to satisfy the related tax withholding and remittance obligations. These payments are reflected as a decrease to additional paid-in capital. The table below presents our pro forma condensed consolidated balance sheet data (in thousands except per share amounts): March 31, 2019 Actual Pro Forma Adjustments Pro Forma Other liabilities $ 23,945 $ (5,005 ) $ 18,940 Redeemable convertible preferred stock, $0.00001 par value, 928,676 shares authorized; 308,373 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares authorized, issued and outstanding, pro forma 1,465,399 (1,465,399 ) — Stockholders’ equity (deficit): Common stock, $0.00001 par value, 1,932,500 shares authorized; 127,371 and 127,298 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares issued and outstanding, pro forma 1 (1 ) — Class A common stock, $0.00001 par value, no shares authorized, issued and outstanding as of March 31, 2019 and December 31, 2018; 6,666,667 shares authorized, 86,250 shares issued and outstanding, pro forma; Class B common stock, $0.00001 par value, no shares authorized, issued and outstanding as of March 31, 2019 and December 31, 2018; 1,333,333 shares authorized, 456,214 shares issued and outstanding, pro forma — 5 5 Additional paid-in capital 253,016 3,706,496 3,959,512 Accumulated other comprehensive loss (231 ) — (231 ) Accumulated deficit (886,775 ) (974,851 ) (1,861,626 ) Total stockholders’ equity (deficit) $ (633,989 ) $ 2,731,649 $ 2,097,660

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Consolidation	We prepared the accompanying condensed consolidated financial statements in accordance with generally accepted accounting principles in the United States ("GAAP"). The condensed consolidated financial statements include the accounts of Pinterest, Inc. and its wholly owned subsidiaries. We have eliminated all intercompany balances and transactions. The condensed consolidated balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. We have condensed or omitted certain information and notes normally included in complete financial statements prepared in accordance with GAAP. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2018 , which are included in our prospectus filed pursuant to Rule 424(b) on April 18, 2019. In our opinion, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but they are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2019 .
Basis of Presentation	We prepared the accompanying condensed consolidated financial statements in accordance with generally accepted accounting principles in the United States ("GAAP"). The condensed consolidated financial statements include the accounts of Pinterest, Inc. and its wholly owned subsidiaries. We have eliminated all intercompany balances and transactions. The condensed consolidated balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. We have condensed or omitted certain information and notes normally included in complete financial statements prepared in accordance with GAAP. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2018 , which are included in our prospectus filed pursuant to Rule 424(b) on April 18, 2019. In our opinion, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but they are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2019 .
Use of Estimates	Preparing our condensed consolidated financial statements in conformity with GAAP requires us to make estimates and judgments that affect amounts reported in the condensed consolidated financial statements and accompanying notes. We base these estimates and judgments on historical experience and various other assumptions that we consider reasonable. GAAP requires us to make estimates and assumptions in several areas, including the fair values of financial instruments, assets acquired and liabilities assumed through business combinations, common stock prior to our IPO and share-based awards, and contingencies as well as the collectability of our accounts receivable, the useful lives of our intangible assets and property and equipment, the incremental borrowing rate we use to determine our operating lease liabilities, and revenue recognition, among others. Actual results could differ materially from these estimates and judgments.
Segments	We operate as a single operating segment. Our chief operating decision maker is our Chief Executive Officer, who reviews financial information presented on a consolidated basis, accompanied by disaggregated information about our revenue, for purposes of making operating decisions, assessing financial performance and allocating resources.
Revenue Recognition	We generate revenue by delivering ads on our website and mobile application. We recognize revenue only after transferring control of promised goods or services to customers, which occurs when a user clicks on an ad contracted on a cost per click (“CPC”) basis or views an ad contracted on a cost per thousand impressions (“CPM”) basis. We typically bill customers on a CPC or CPM basis, and our payment terms vary by customer type and location. The term between billing and payment due dates is not significant. We occasionally offer customers free ad inventory or measurement studies that demonstrate the effectiveness of their advertising campaigns on our platform. In either case, we recognize revenue only after satisfying our contractual performance obligation. When contracts with our customers contain multiple performance obligations, we allocate the overall transaction price, which is the amount of consideration to which we expect to be entitled in exchange for promised goods or services, to each of the distinct performance obligations based on their relative standalone selling prices. We generally determine standalone selling prices based on the effective price charged per contracted click or impression or based on expected cost plus margin, and we do not disclose the value of unsatisfied performance obligations because the original expected duration of our contracts is generally less than one year. We record sales commissions in sales and marketing expense as incurred because we would amortize these over a period of less than one year.
Share-Based Compensation	We have granted restricted stock units ("RSUs") since March 2015. We measure RSUs based on the fair market value of our common stock on the grant date. RSUs granted under our 2009 Stock Plan (the "2009 Plan") are subject to both a service condition, which is typically satisfied over four years , and a performance condition, which was deemed satisfied upon the pricing of the shares of Class A common stock sold in connection with our IPO. Because the performance condition had not been satisfied as of March 31, 2019 , we had not recorded any share-based compensation expense for our RSUs at that date. Had our IPO occurred on March 31, 2019, we would have recorded cumulative share-based compensation expense using the accelerated attribution method for those RSUs for which the service condition had been satisfied at that date and would have begun recording the remaining unrecognized share-based compensation expense over the remainder of the requisite service period. We account for forfeitures as they occur.
Valuation of Common Stock and Redeemable Convertible Preferred Stock Warrants	Until our IPO, we determined the fair value of our common stock and redeemable convertible preferred stock warrants using the most observable inputs available to us, including recent sales of our stock as well as income and market valuation approaches. The income approach estimates the value of our business based on the future cash flows we expect to generate discounted to their present value using an appropriate discount rate to reflect the risk of achieving the expected cash flows. The market approach estimates the value of our business by applying valuation multiples derived from the observed valuation multiples of comparable public companies to our expected financial results. We used the Probability Weighted Expected Return Method ("PWERM") to allocate the value of our business among our outstanding stock and share-based awards. We applied the PWERM by first defining the range of potential future liquidity outcomes for our business, such as an IPO, and then allocating its value to our outstanding stock and share-based awards based on the relative probability that each outcome will occur. We used the Option Pricing Method to allocate the value of our business to our outstanding stock and share-based awards under the non-IPO outcome we considered within the PWERM. Applying these valuation and allocation approaches involved the use of estimates, judgments, and assumptions that are highly complex and subjective, such as those regarding our expected future revenue, expenses, and cash flows, discount rates, valuation multiples, the selection of comparable public companies, and the probability of future events. Changes in any or all of these estimates and assumptions, or the relationships between these assumptions, impacted our valuation as of each valuation date and may have a material impact on the valuation of our common stock and redeemable convertible preferred stock warrants. Following our IPO, there is an active market for our Class A common stock and the warrants to purchase shares of our redeemable convertible preferred stock are no longer outstanding, so we no longer apply these valuation and allocation approaches.
Incremental Borrowing Rate	We lease office space under operating leases with expiration dates through 2033 . We determine whether an arrangement constitutes a lease and record lease liabilities and right-of-use assets on our condensed consolidated balance sheets at lease commencement. We measure lease liabilities based on the present value of the total lease payments not yet paid discounted based on the more readily determinable of the rate implicit in the lease or our incremental borrowing rate, which is the estimated rate we would be required to pay for a collateralized borrowing equal to the total lease payments over the term of the lease. We estimate our incremental borrowing rate based on an analysis of publicly traded debt securities of companies with credit and financial profiles similar to our own. We measure right-of-use assets based on the corresponding lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs we incur and (iii) tenant incentives under the lease. We begin recognizing rent expense when the lessor makes the underlying asset available to us, we do not assume renewals or early terminations unless we are reasonably certain to exercise these options at commencement, and we do not allocate consideration between lease and non-lease components. For short-term leases, we record rent expense in our condensed consolidated statements of operations on a straight-line basis over the lease term and record variable lease payments as incurred.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair value on a recurring basis	The fair values of the financial instruments we measure at fair value on a recurring basis are as follows (in thousands): March 31, 2019 Level 1 Level 2 Level 3 Total Cash equivalents: Commercial paper $ — $ 76,897 $ — $ 76,897 Money market funds 546 — — 546 Marketable securities: Corporate bonds — 214,819 — 214,819 Asset-backed securities — 108,059 — 108,059 Certificates of deposit — 64,418 — 64,418 Commercial paper — 100,212 — 100,212 U.S. treasury securities 20,060 — — 20,060 Prepaid expenses and other current assets: Certificates of deposit — 1,057 — 1,057 Restricted cash: Certificates of deposit — 25,724 — 25,724 Other liabilities: Redeemable convertible preferred stock warrants $ — $ — $ 5,005 $ 5,005 December 31, 2018 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 785 $ — $ — $ 785 Commercial paper — 73,486 — 73,486 Marketable securities: Corporate bonds — 204,170 — 204,170 U.S. treasury securities 35,921 — — 35,921 Asset-backed securities — 106,658 — 106,658 Certificates of deposit — 68,359 — 68,359 Commercial paper — 90,196 — 90,196 Prepaid expenses and other current assets: Certificates of deposit — 1,057 — 1,057 Restricted cash: Certificates of deposit — 11,724 — 11,724 Other liabilities: Redeemable convertible preferred stock warrants $ — $ — $ 4,934 $ 4,934
Fair value of our marketable securities by contractual maturity	The fair value of our marketable securities by contractual maturity is as follows (in thousands): March 31, 2019 Due in one year or less $ 319,271 Due after one to five years 188,297 Total $ 507,568

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of stock option activity	Stock option activity during the three months ended March 31, 2019 , was as follows (in thousands, except per share amounts): Stock Options Outstanding Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (1) (in years) Outstanding as of December 31, 2018 76,635 $ 2.22 4.5 $ 1,285,338 Exercised (73) 2.58 Forfeited (6) 3.84 Outstanding as of March 31, 2019 76,556 $ 2.22 4.3 $ 1,339,176 Exercisable as of March 31, 2019 76,351 $ 2.21 4.3 $ 1,335,964 (1) We calculate intrinsic value based on the difference between the exercise price of in-the-money-stock options and the fair value of our common stock as of the respective balance sheet date.
Schedule of restricted stock unit activity	RSU activity during the three months ended March 31, 2019 , was as follows (in thousands, except per share amounts): Restricted Stock Units Outstanding Shares Weighted Average Grant Date Fair Value Outstanding as of December 31, 2018 77,882 $ 17.79 Granted 28,531 19.60 Forfeited (2,486) 18.43 Outstanding as of March 31, 2019 103,927 $ 18.27
Schedule of share-based compensation	Share-based compensation expense during the three months ended March 31, 2019 and 2018 , was as follows (in thousands): Three Months Ended March 31, 2019 2018 Cost of revenue $ 15 $ 32 Research and development 626 4,054 Sales and marketing 29 241 General and administrative 24 507 Total share-based compensation $ 694 $ 4,834

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Basic and diluted net loss per share attributable to common stockholders	We calculated basic and diluted net loss per share attributable to common stockholders as follows (in thousands, except per share amounts): Three Months Ended March 31, 2019 2018 Numerator: Net loss attributable to common stockholders $ (41,420 ) $ (52,709 ) Denominator: Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 127,346 126,857 Net loss per share attributable to common stockholders, basic and diluted $ (0.33 ) $ (0.42 )
Schedule of anti-dilutive shares	Basic net loss per share is the same as diluted net loss per share because we reported net losses for all periods presented. We excluded the following weighted-average potential shares of common stock from our calculation of diluted net loss per share attributable to common stockholders because these would be anti-dilutive (in thousands): Three Months Ended March 31, 2019 2018 Redeemable convertible preferred stock 308,373 308,373 Outstanding stock options 76,584 77,341 Unvested restricted stock units 81,498 58,447 Redeemable convertible preferred stock warrants 249 89 Common stock warrants — 167 Total 466,704 444,417

Geographical Information (Table

Geographical Information (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Revenue disaggregated by geography	Revenue disaggregated by geography based on our customers’ billing addresses is as follows (in thousands): Three Months Ended March 31, 2019 2018 United States $ 181,762 $ 121,382 International (1) 20,149 9,977 Total revenue $ 201,911 $ 131,359 (1) No individual country other than the United States exceeded 10% of our total revenue for any period presented.
Property and equipment, net by geography	Property and equipment, net and operating lease right-of-use assets by geography is as follows (in thousands): March 31, December 31, 2019 2018 United States $ 234,794 $ 222,188 International (1) 9,039 4,527 Total property and equipment, net and operating lease right-of-use assets $ 243,833 $ 226,715 (1) No individual country other than the United States exceeded 10% of our total property and equipment, net for any period presented.

Subsequent Events (Tables)

Subsequent Events (Tables)	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Balance Sheet, Pro Forma Information	The table below presents our pro forma condensed consolidated balance sheet data (in thousands except per share amounts): March 31, 2019 Actual Pro Forma Adjustments Pro Forma Other liabilities $ 23,945 $ (5,005 ) $ 18,940 Redeemable convertible preferred stock, $0.00001 par value, 928,676 shares authorized; 308,373 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares authorized, issued and outstanding, pro forma 1,465,399 (1,465,399 ) — Stockholders’ equity (deficit): Common stock, $0.00001 par value, 1,932,500 shares authorized; 127,371 and 127,298 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares issued and outstanding, pro forma 1 (1 ) — Class A common stock, $0.00001 par value, no shares authorized, issued and outstanding as of March 31, 2019 and December 31, 2018; 6,666,667 shares authorized, 86,250 shares issued and outstanding, pro forma; Class B common stock, $0.00001 par value, no shares authorized, issued and outstanding as of March 31, 2019 and December 31, 2018; 1,333,333 shares authorized, 456,214 shares issued and outstanding, pro forma — 5 5 Additional paid-in capital 253,016 3,706,496 3,959,512 Accumulated other comprehensive loss (231 ) — (231 ) Accumulated deficit (886,775 ) (974,851 ) (1,861,626 ) Total stockholders’ equity (deficit) $ (633,989 ) $ 2,731,649 $ 2,097,660

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies - Initial Public Offering (Details) - Subsequent event - USD ($) $ / shares in Units, $ in Millions	Apr. 29, 2019	Apr. 23, 2019	Apr. 22, 2019
Class A common stock | IPO
Subsidiary, Sale of Stock [Line Items]
Shares sold (in shares)		75,000,000
Share price (in dollars per share)		$ 19
Net proceeds		$ 1,368
Estimated offering costs		8.7
Class A common stock | Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares sold (in shares)	11,250,000
Share price (in dollars per share)	$ 19
Net proceeds	$ 205.2
Class A common stock | Other assets | IPO
Subsidiary, Sale of Stock [Line Items]
Offering costs		$ 5.6
Redeemable Convertible Preferred Stock And Redeemable Convertible Preferred Stock Warrants Converted | Class B common stock
Subsidiary, Sale of Stock [Line Items]
Shares converted (in shares)			1
Shares issued in conversion (in shares)			308,621,636
Common Stock Reclassified Into Class B Common Stock | Class B common stock
Subsidiary, Sale of Stock [Line Items]
Shares converted (in shares)			1
Shares issued in conversion (in shares)			456,213,756

Description of Business and S_4

Description of Business and Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2019segment
Accounting Policies [Abstract]
Reverse stock split ratio	0.33
Number of operating segments	1
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	4 years

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 507,568
Commercial paper | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	76,897	$ 73,486
Commercial paper | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Commercial paper | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	76,897	73,486
Commercial paper | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Money market funds | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	546	785
Money market funds | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	546	785
Money market funds | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Money market funds | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Corporate bonds | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	214,819	204,170
Corporate bonds | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Corporate bonds | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	214,819	204,170
Corporate bonds | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Asset-backed securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	108,059	106,658
Asset-backed securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Asset-backed securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	108,059	106,658
Asset-backed securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Certificates of deposit | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	64,418	68,359
Prepaid expenses and other current assets	1,057	1,057
Restricted cash	25,724	11,724
Certificates of deposit | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Prepaid expenses and other current assets	0	0
Restricted cash	0	0
Certificates of deposit | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	64,418	68,359
Prepaid expenses and other current assets	1,057	1,057
Restricted cash	25,724	11,724
Certificates of deposit | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Prepaid expenses and other current assets	0	0
Restricted cash	0	0
Commercial paper | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	100,212	90,196
Commercial paper | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Commercial paper | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	100,212	90,196
Commercial paper | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
U.S. treasury securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	20,060	35,921
U.S. treasury securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	20,060	35,921
U.S. treasury securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
U.S. treasury securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Redeemable convertible preferred stock warrants | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	5,005	4,934
Redeemable convertible preferred stock warrants | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	0	0
Redeemable convertible preferred stock warrants | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	0	0
Redeemable convertible preferred stock warrants | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other liabilities	$ 5,005	$ 4,934

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Fair Value Maturity (Details) $ in Thousands	Mar. 31, 2019USD ($)
Fair Value Disclosures [Abstract]
Due in one year or less	$ 319,271
Due after one to five years	188,297
Total	$ 507,568

Commitments and Contingencies (

Commitments and Contingencies (Details) ft² in Thousands, $ in Millions	Mar. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Area of office space (in sqft) | ft²	490
Noncancelable minimum lease payments not yet commenced	$ 420
Secured letters of credit outstanding	$ 24.6	$ 10.6

Share-Based Compensation - Equi

Share-Based Compensation - Equity Incentive Plan (Details) - shares	Apr. 23, 2019	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of outstanding shares, additional reserve		0.05
2009 Plan | Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance (in shares)		22,641,049
2009 Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period		10 years
2009 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period		7 years
2019 Plan | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance (in shares)		48,200,000
Subsequent event | Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld to satisfy tax withholding	15,966,336
Subsequent event | 2019 Plan | Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance (in shares)	86,807,385

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Shares
Beginning balance (in shares)	76,635
Exercised (in shares)	(73)
Forfeited (in shares)	(6)
Ending balance (in shares)	76,556	76,635
Exercisable (in shares)	76,351
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 2.22
Exercised (in dollars per share)	2.58
Forfeited (in dollars per share)	3.84
Ending balance (in dollars per share)	2.22	$ 2.22
Exercisable (in dollars per share)	$ 2.21
Weighted-Average Remaining Contractual Term, Outstanding	4 years 3 months 18 days	4 years 6 months
Weighted-Average Remaining Contractual Term, Exercisable	4 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding	$ 1,339,176	$ 1,285,338
Aggregate Intrinsic Value, Exercisable	$ 1,335,964

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant-date fair value of stock options vested	$ 0.6	$ 18.6
Aggregate intrinsic value of stock options exercised	$ 1.2	$ 5.9
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	4 years
Pro Forma | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated share-based compensation	$ 974.9
Unrecognized share-based compensation expense	$ 924.5
Unrecognized share-based compensation expense, weighted average period	3 years 8 months 12 days

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Unit Activity (Details) - RSUs shares in Thousands	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Shares
Beginning balance (in shares) | shares	77,882
Granted (in shares) | shares	28,531
Forfeited (in shares) | shares	(2,486)
Ending balance (in shares) | shares	103,927
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 17.79
Granted (in dollars per share) | $ / shares	19.60
Forfeited (in dollars per share) | $ / shares	18.43
Ending balance (in dollars per share) | $ / shares	$ 18.27

Share-Based Compensation - Shar

Share-Based Compensation - Share-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	$ 694	$ 4,834
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	15	32
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	626	4,054
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	29	241
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation	$ 24	$ 507

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net loss attributable to common stockholders	$ (41,420)	$ (52,709)
Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	127,346	126,857
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.33)	$ (0.42)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Anti-dilutive Shares (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	466,704	444,417
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	308,373	308,373
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	76,584	77,341
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	81,498	58,447
Redeemable convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	249	89
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	0	167

Geographical Information (Detai

Geographical Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 201,911	$ 131,359
Total property and equipment, net and operating lease right-of-use assets	243,833		$ 226,715
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	181,762	121,382
Total property and equipment, net and operating lease right-of-use assets	234,794		222,188
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	20,149	$ 9,977
Total property and equipment, net and operating lease right-of-use assets	$ 9,039		$ 4,527

Subsequent Events - Initial Pub

Subsequent Events - Initial Public Offering (Details) $ / shares in Units, $ in Thousands	Apr. 29, 2019USD ($)$ / sharesshares	Apr. 23, 2019USD ($)$ / sharesshares	Apr. 22, 2019shares	Mar. 31, 2019USD ($)voteshares	Mar. 31, 2018USD ($)
Subsequent Event [Line Items]
Share-based compensation expense				$ 694	$ 4,834
Class A common stock
Subsequent Event [Line Items]
Voting rights per share | vote				1
Class A common stock | IPO | Subsequent event
Subsequent Event [Line Items]
Shares sold (in shares) | shares		75,000,000
Share price (in dollars per share) | $ / shares		$ 19
Net proceeds		$ 1,368,000
Estimated offering costs		8,700
Class A common stock | Over-Allotment Option | Subsequent event
Subsequent Event [Line Items]
Shares sold (in shares) | shares	11,250,000
Share price (in dollars per share) | $ / shares	$ 19
Net proceeds	$ 205,200
Class A common stock | Other assets | IPO | Subsequent event
Subsequent Event [Line Items]
Offering costs		$ 5,600
Class B common stock
Subsequent Event [Line Items]
Voting rights per share | vote				20
Redeemable Convertible Preferred Stock And Redeemable Convertible Preferred Stock Warrants Converted | Class B common stock | Subsequent event
Subsequent Event [Line Items]
Shares issued in conversion (in shares) | shares			308,621,636
Shares converted (in shares) | shares			1
Common Stock Reclassified Into Class B Common Stock | Class B common stock | Subsequent event
Subsequent Event [Line Items]
Shares issued in conversion (in shares) | shares			456,213,756
Shares converted (in shares) | shares			1
RSUs
Subsequent Event [Line Items]
Service period				4 years
Pro Forma | Class A common stock | IPO
Subsequent Event [Line Items]
Net proceeds				$ 1,573,200
Estimated offering costs				8,700
Underwriting discounts and commissions				$ 65,600
Pro Forma | Class B common stock
Subsequent Event [Line Items]
Shares released (in shares) | shares				20,221,114
Pro Forma | RSUs
Subsequent Event [Line Items]
Share-based compensation expense				$ 974,900
Cash payments for tax withholding				$ 303,300

Subsequent Events - Pro Forma (

Subsequent Events - Pro Forma (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Other liabilities	$ 23,945	$ 22,073
Redeemable convertible preferred stock, $0.00001 par value, 928,676 shares authorized; 308,373 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares authorized, issued and outstanding, pro forma	1,465,399	1,465,399	$ 1,465,399	$ 1,465,399
Common stock	1	1
Additional paid-in capital	253,016	252,212
Accumulated other comprehensive loss	(231)	(1,421)
Accumulated deficit	(886,775)	(845,355)
Total stockholders’ equity (deficit)	(633,989)	$ (594,563)	$ (594,963)	$ (546,464)
Pro Forma Adjustments
Subsequent Event [Line Items]
Other liabilities	(5,005)
Redeemable convertible preferred stock, $0.00001 par value, 928,676 shares authorized; 308,373 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares authorized, issued and outstanding, pro forma	(1,465,399)
Common stock	(1)
Additional paid-in capital	3,706,496
Accumulated other comprehensive loss	0
Accumulated deficit	(974,851)
Total stockholders’ equity (deficit)	2,731,649
Pro Forma
Subsequent Event [Line Items]
Other liabilities	18,940
Redeemable convertible preferred stock, $0.00001 par value, 928,676 shares authorized; 308,373 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; no shares authorized, issued and outstanding, pro forma	0
Common stock	0
Additional paid-in capital	3,959,512
Accumulated other comprehensive loss	(231)
Accumulated deficit	(1,861,626)
Total stockholders’ equity (deficit)	2,097,660
Class A common stock
Subsequent Event [Line Items]
Common stock	0
Class A common stock | Pro Forma Adjustments
Subsequent Event [Line Items]
Common stock	5
Class A common stock | Pro Forma
Subsequent Event [Line Items]
Common stock	5
Class B common stock
Subsequent Event [Line Items]
Common stock	0
Class B common stock | Pro Forma Adjustments
Subsequent Event [Line Items]
Common stock	5
Class B common stock | Pro Forma
Subsequent Event [Line Items]
Common stock	$ 5

Subsequent Events - Pro Forma S

Subsequent Events - Pro Forma Stock (Details) - $ / shares	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Redeemable convertible preferred stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Redeemable convertible preferred stock, Shares authorized (in shares)	928,676,000	928,676,000
Redeemable convertible preferred stock, Shares issued (in shares)	308,373,000	308,373,000
Redeemable convertible preferred stock, Shares outstanding (in shares)	308,373,000	308,373,000	308,373,000	308,373,000
Common Stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Common Stock, Shares authorized (in shares)	1,932,500,000	1,932,500,000
Common Stock, Shares issued (in shares)	127,371,000	127,298,000
Common Stock, Shares outstanding (in shares)	127,371,000	127,298,000
Pro Forma
Subsequent Event [Line Items]
Redeemable convertible preferred stock, Shares authorized (in shares)	0	0
Redeemable convertible preferred stock, Shares issued (in shares)	0	0
Redeemable convertible preferred stock, Shares outstanding (in shares)	0	0
Common Stock, Shares issued (in shares)	0	0
Common Stock, Shares outstanding (in shares)	0	0
Class A common stock
Subsequent Event [Line Items]
Common Stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Common Stock, Shares authorized (in shares)	0	0
Common Stock, Shares issued (in shares)	0	0
Common Stock, Shares outstanding (in shares)	0	0
Class A common stock | Pro Forma
Subsequent Event [Line Items]
Common Stock, Shares authorized (in shares)	6,666,667,000	6,666,667,000
Common Stock, Shares issued (in shares)	86,250,000	86,250,000
Common Stock, Shares outstanding (in shares)	86,250,000	86,250,000
Class B common stock
Subsequent Event [Line Items]
Common Stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Common Stock, Shares authorized (in shares)	0	0
Common Stock, Shares issued (in shares)	0	0
Common Stock, Shares outstanding (in shares)	0	0
Class B common stock | Pro Forma
Subsequent Event [Line Items]
Common Stock, Par value (in dollars per share)	$ 0.00001	$ 0.00001
Common Stock, Shares authorized (in shares)	1,333,333,000	1,333,333,000
Common Stock, Shares issued (in shares)	456,214,000	456,214,000
Common Stock, Shares outstanding (in shares)	456,214,000	456,214,000