Twitter (TWTR) 10-K 17 Feb 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 09, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Transition Report	false
Amendment Flag	false
Entity Central Index Key	0001418091
Entity File Number	001-36164
Entity Registrant Name	Twitter, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8913779
Entity Address, Address Line One	1355 Market Street
Entity Address, Address Line Two	Suite 900
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94103
City Area Code	415
Local Phone Number	222-9670
Title of 12(b) Security	Common Stock, par value $0.000005 per share
Trading Symbol	TWTR
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Fiscal Year Focus	2020
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 23,020
Entity Common Stock, Shares Outstanding		798,152,488

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and Cash Equivalents	$ 1,988,429	$ 1,799,082
Short-term investments	5,483,873	4,839,970
Accounts receivable, net of allowance for doubtful accounts of $16,946 and $2,401	1,041,743	850,184
Prepaid expenses and other current assets	123,063	130,839
Total current assets	8,637,108	7,620,075
Property and equipment, net	1,493,794	1,031,781
Operating lease right-of-use assets	930,139	697,095
Intangible assets, net	58,338	55,106
Goodwill	1,312,346	1,256,699
Deferred tax assets, net	796,326	1,908,086
Other assets	151,039	134,547
Total assets	13,379,090	12,703,389
Current liabilities:
Accounts payable	194,281	161,148
Accrued and other current liabilities	662,965	500,893
Convertible notes, short-term	917,866	0
Operating lease liabilities, short-term	177,147	146,959
Finance lease liabilities, short-term	567	23,476
Total current liabilities	1,952,826	832,476
Convertible notes, long-term	1,875,878	1,816,833
Senior notes, long-term	692,994	691,967
Operating lease liabilities, long-term	819,748	609,245
Deferred and other long-term tax liabilities, net	31,463	24,170
Other long-term liabilities	36,099	24,312
Total liabilities	5,409,008	3,999,003
Commitments and contingencies (Note 16)
Stockholders' equity:
Preferred stock, $0.000005 par value-- 200,000 shares authorized; none issued and outstanding	0	0
Common stock, $0.000005 par value-- 5,000,000 shares authorized; 796,000 and 779,619 shares issued and outstanding	4	4
Additional paid-in capital	9,167,138	8,763,330
Treasury stock, at cost-- 98 and 0 shares	(5,297)	0
Accumulated other comprehensive loss	(66,094)	(70,534)
Retained earnings (accumulated deficit)	(1,125,669)	11,586
Total stockholders' equity	7,970,082	8,704,386
Total liabilities and stockholders' equity	$ 13,379,090	$ 12,703,389

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 16,946	$ 2,401
Preferred shares, par value (in dollars per share)	$ 0.000005	$ 0.000005
Preferred shares, authorized (in shares)	200,000,000	200,000,000
Preferred shares, issued (in shares)	0	0
Preferred shares, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.000005	$ 0.000005
Common shares, authorized (in shares)	5,000,000,000	5,000,000,000
Common shares, issued (in shares)	796,000,000	779,619,000
Common shares, outstanding (in shares)	796,000,000	779,619,000
Treasury stock (in shares)	98,000	0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 3,716,349	$ 3,459,329	$ 3,042,359
Costs and expenses
Cost of revenue	1,366,388	1,137,041	964,997
Research and development	873,011	682,281	553,858
Sales and marketing	887,860	913,813	771,361
General and administrative	562,432	359,821	298,818
Total costs and expenses	3,689,691	3,092,956	2,589,034
Income from operations	26,658	366,373	453,325
Interest expense	(152,878)	(138,180)	(132,606)
Interest income	88,178	157,703	111,221
Other income (expense), net	(12,897)	4,243	(8,396)
Income (loss) before income taxes	(50,939)	390,139	423,544
Provision (benefit) for income taxes	1,084,687	(1,075,520)	(782,052)
Net income (loss)	$ (1,135,626)	$ 1,465,659	$ 1,205,596
Net income (loss) per share attributable to common stockholders:
Basic (in dollars per share)	$ (1.44)	$ 1.90	$ 1.60
Diluted (in dollars per share)	$ (1.44)	$ 1.87	$ 1.56
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders:
Basic (in shares)	787,861	770,729	754,326
Diluted (in shares)	787,861	785,531	772,686

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (1,135,626)	$ 1,465,659	$ 1,205,596
Other comprehensive income (loss), net of tax:
Change in unrealized gain (loss) on investments in available-for-sale securities	11,318	13,785	(393)
Change in foreign currency translation adjustment	(6,878)	(19,008)	(33,339)
Net change in accumulated other comprehensive income (loss)	4,440	(5,223)	(33,732)
Comprehensive income (loss)	$ (1,131,186)	$ 1,460,436	$ 1,171,864

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Retained earnings (accumulated deficit)	Retained earnings (accumulated deficit)Cumulative Effect, Period of Adoption, Adjustment
Balance, beginning of period, shares at Dec. 31, 2017		746,902,000
Balance, beginning of period at Dec. 31, 2017		$ 4	$ 7,750,522		$ (31,579)	$ (2,671,729)	$ 12,060
Issuance of common stock in connection with RSU vesting, shares		15,026,000
Issuance of common stock in connection with acquisitions, shares		119,000
Issuance of restricted stock in connection with acquisitions accounted for as stock-based compensation, shares		655,000
Issuance of common stock in connection with acquisitions			18,248
Issuance of stock options in connection with acquisitions			917
Exercise of stock options, shares		634,000
Exercise of stock options			3,442
Issuance of common stock upon purchases under employee stock purchase plan, shares		1,539,000
Issuance of common stock upon purchases under employee stock purchase plan			29,288
Shares withheld related to net share settlement of equity awards, shares		(610,000)
Shares withheld related to net share settlement of equity awards			(19,256)
Stock-based compensation			367,668
Equity component of the convertible note issuance, net			252,248
Purchase of convertible note hedge	$ (267,950)		(267,950)
Issuance of warrants			186,760
Other activities, shares		(8,000)
Other activities			3,087
Other comprehensive income (loss)	(33,732)				(33,732)
Net income (loss)	$ 1,205,596					1,205,596
Balance, end of period, shares at Dec. 31, 2018	764,257,000	764,257,000
Balance, end of period at Dec. 31, 2018	$ 6,805,594	$ 4	8,324,974		(65,311)	(1,454,073)
Issuance of common stock in connection with RSU vesting, shares		13,519,000
Issuance of restricted stock in connection with acquisitions accounted for as stock-based compensation, shares		471,000
Issuance of common stock in connection with acquisitions			0
Issuance of stock options in connection with acquisitions			0
Exercise of stock options, shares		361,000
Exercise of stock options			788
Issuance of common stock upon purchases under employee stock purchase plan, shares	1,600,000	1,592,000
Issuance of common stock upon purchases under employee stock purchase plan			42,378
Shares withheld related to net share settlement of equity awards, shares		(579,000)
Shares withheld related to net share settlement of equity awards			(19,594)
Stock-based compensation			414,784
Equity component of the convertible note issuance, net			0
Purchase of convertible note hedge	$ 0		0
Issuance of warrants			0
Other activities, shares		(2,000)
Other activities			0
Other comprehensive income (loss)	(5,223)				(5,223)
Net income (loss)	$ 1,465,659					1,465,659
Balance, end of period, shares at Dec. 31, 2019	779,619,000	779,619,000
Balance, end of period at Dec. 31, 2019	$ 8,704,386	$ 4	8,763,330	$ 0	(70,534)	11,586	$ (1,629)
Issuance of common stock in connection with RSU vesting, shares		16,795,000
Issuance of common stock in connection with acquisitions, shares		168,000
Issuance of restricted stock in connection with acquisitions accounted for as stock-based compensation, shares		1,509,000
Issuance of common stock in connection with acquisitions			8,311
Exercise of stock options, shares	1,882,000	1,882,000
Exercise of stock options			5,441
Issuance of common stock upon purchases under employee stock purchase plan, shares	2,300,000	2,250,000
Issuance of common stock upon purchases under employee stock purchase plan			55,470
Shares withheld related to net share settlement of equity awards, shares		(639,000)
Shares withheld related to net share settlement of equity awards			(22,585)
Stock-based compensation			510,254
Equity component of the convertible note issuance, net			92,209
Purchase of convertible note hedge	$ 0
Repurchased of common stock, shares	5,700,000	(5,584,000)
Repurchases of common stock	$ 250,600		(245,292)	(5,297)
Other activities, shares		0
Other comprehensive income (loss)	4,440				4,440
Net income (loss)	$ (1,135,626)					(1,135,626)
Balance, end of period, shares at Dec. 31, 2020	796,000,000	796,000,000
Balance, end of period at Dec. 31, 2020	$ 7,970,082	$ 4	$ 9,167,138	$ (5,297)	$ (66,094)	$ (1,125,669)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income (loss)	$ (1,135,626)	$ 1,465,659	$ 1,205,596
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization expense	495,177	465,549	425,498
Stock-based compensation expense	474,932	378,025	326,228
Amortization of discount on convertible notes	101,733	113,298	105,926
Bad debt expense	18,775	3,083	1,610
Deferred income taxes	(36,978)	84,369	43,409
Deferred tax assets valuation allowance release	0	0	845,129
Deferred tax assets establishment related to intra-entity transfers of intangible assets	0	(1,206,880)	0
Deferred tax assets valuation allowance establishment	1,101,374	0	0
Impairment of investments in privately-held companies	8,842	1,550	3,000
Other adjustments	(10,764)	(19,989)	(15,749)
Changes in assets and liabilities, net of assets acquired and liabilities assumed from acquisitions:
Accounts receivable	(188,039)	(67,000)	(130,871)
Prepaid expenses and other assets	6,398	(29,602)	126,470
Operating lease right-of-use assets	168,000	149,880	0
Accounts payable	18,232	2,946	(1,533)
Accrued and other liabilities	123,345	92,681	95,256
Operating lease liabilities	(152,531)	(130,205)	0
Net cash provided by operating activities	992,870	1,303,364	1,339,711
Cash flows from investing activities
Purchases of property and equipment	(873,354)	(540,688)	(483,934)
Proceeds from sales of property and equipment	9,170	6,158	13,070
Purchases of marketable securities	(6,272,395)	(5,798,111)	(5,334,396)
Proceeds from maturities of marketable securities	4,554,238	4,928,097	3,732,973
Proceeds from sales of marketable securities	1,092,754	367,116	58,721
Purchases of investments in privately-held companies	(11,912)	(51,163)	(3,375)
Proceeds from sales of long-lived assets	0	11,781	0
Business combinations, net of cash acquired	(48,016)	(29,664)	(33,572)
Other investing activities	(11,050)	(9,500)	(5,000)
Net cash used in investing activities	(1,560,565)	(1,115,974)	(2,055,513)
Cash flows from financing activities
Proceeds from issuance of convertible notes	1,000,000	0	1,150,000
Proceeds from issuance of senior notes	0	700,000	0
Purchases of convertible note hedges	0	0	(267,950)
Proceeds from issuance of warrants concurrent with note hedges	0	0	186,760
Debt issuance costs	(14,662)	(8,070)	(13,783)
Repayment of convertible notes	0	(935,000)	0
Repurchases of common stock	(245,292)	0	0
Taxes paid related to net share settlement of equity awards	(22,587)	(19,594)	(19,263)
Payments of finance lease obligations	(23,062)	(66,677)	(90,351)
Proceeds from exercise of stock options	5,442	788	3,415
Proceeds from issuances of common stock under employee stock purchase plan	55,471	42,378	29,288
Net cash provided by (used in) financing activities	755,310	(286,175)	978,116
Net increase (decrease) in cash, cash equivalents and restricted cash	187,615	(98,785)	262,314
Foreign exchange effect on cash, cash equivalents and restricted cash	(4,005)	4,576	(14,296)
Cash, cash equivalents and restricted cash at beginning of period	1,827,666	1,921,875	1,673,857
Cash, cash equivalents and restricted cash at end of period	2,011,276	1,827,666	1,921,875
Supplemental cash flow data
Interest paid in cash	38,510	12,236	14,547
Income taxes paid in cash	11,480	20,144	33,065
Supplemental disclosures of non-cash investing and financing activities
Common stock issued in connection with acquisitions	8,311	0	19,165
Changes in accrued property and equipment purchases	24,882	14,985	(23,469)
Reconciliation of cash, cash equivalents and restricted cash as shown in the consolidated statements of cash flows
Cash and cash equivalents	1,988,429	1,799,082	1,894,444
Total cash, cash equivalents and restricted cash	$ 1,827,666	$ 1,921,875	$ 1,921,875

The Company

The Company	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
The Company	The CompanyTwitter, Inc. (“Twitter” or the “Company”) was incorporated in Delaware in April 2007, and is headquartered in San Francisco, California. Twitter offers products and services for people, organizations, advertisers, developers and platform and data partners.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Prior Period Reclassifications Certain prior period amounts have been reclassified to conform to the current period presentation. Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with generally accepted accounting principles in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, as well as related disclosure of contingent assets and liabilities. Actual results could differ materially from the Company’s estimates. To the extent that there are material differences between these estimates and actual results, the Company’s financial condition or operating results will be affected. The Company bases its estimates on past experience and other assumptions that the Company believes are reasonable under the circumstances, and the Company evaluates these estimates on an ongoing basis. COVID-19 Impacts The COVID-19 pandemic has caused, and continues to cause, widespread economic disruption and has impacted the Company in a number of ways, most notably a significant decrease in global advertising spend in the first half of 2020, followed by a recovery in the second half of 2020. The Company expects the extent of the impact on its financial and operational results will depend on the duration and severity of the economic disruption caused by the COVID-19 pandemic. As of December 31, 2020, the Company had $7.47 billion of cash, cash equivalents and short-term investments in marketable securities. If required, the Company may take certain liquidity mitigation actions in the future; however, it does not believe such actions are necessary based on its current forecasts. The Company believes that the existing cash, cash equivalents and short-term investments balances, together with cash generated by operations will be sufficient to meet its working capital and capital expenditure requirements in the foreseeable future based on its current expectations of the impact of the COVID-19 pandemic. The Company considered the impacts of the COVID-19 pandemic on its significant estimates and judgments used in applying its accounting policies in 2020. In light of the pandemic, there is a greater degree of uncertainty in applying these judgments and depending on the duration and severity of the pandemic, changes to its estimates and judgments could result in a meaningful impact to its financial statements in future periods. Some of the more reasonably possible and significant items subject to a greater degree of uncertainty during this time include estimates of the valuation allowance against deferred tax assets, the carrying value of investments in privately-held companies, and credit losses related to accounts receivable, unbilled revenue, and investments in debt securities. Revenue Recognition The Company generates the substantial majority of its revenue from the sale of advertising services with the remaining balance from data licensing and other arrangements. The Company generates its advertising revenue primarily from the sale of its Promoted Products: (i) Promoted Tweets, (ii) Promoted Accounts and (iii) Promoted Trends. Promoted Tweets and Promoted Accounts are pay-for-performance advertising products or pay on impressions delivered, each priced through an auction. Promoted Trends are featured by geography and offered on a fixed-fee-per-day basis. Advertisers are obligated to pay when a person engages with a Promoted Tweet, follows a Promoted Account, when an impression is delivered, or when a Promoted Trend is displayed for an entire day in a particular country or on a global basis. These advertising services may be sold in combination as a bundled arrangement or separately on a stand-alone basis. For the Company's Promoted Product arrangements, significant judgments are (i) identifying the performance obligations in the contract, (ii) determining the basis for allocating contract consideration to performance obligations, (iii) determining whether the Company is the principal or the agent in arrangements where another party is involved in providing specified services to a customer, and (iv) estimating the transaction price to be allocated for contracts with tiered rebate provisions. The Company may generate revenue from the sale of certain Promoted Tweets through placement by Twitter of advertiser ads against third-party publisher content. The Company will pay the third-party publisher a revenue share fee for its right to monetize their content. In such transactions, advertisers are contracting to obtain a single integrated advertising service, the Promoted Tweet combined with the third-party publisher content, and the Company obtains control of the third-party publisher content displayed on Twitter that it then combines with the advertiser ads within the Promoted Tweet. Therefore, the Company reports advertising revenue generated from these transactions on a gross basis and records the related third-party content monetization fees as cost of revenue. The Company also generates advertising revenue by selling services in which the Company places ads on third-party publishers’ websites, applications or other offerings. To fulfill these transactions, the Company purchases advertising inventory from third-party publishers’ websites and applications where the Company has identified the advertisers’ targeted audience and therefore incurs traffic acquisition costs prior to transferring the advertising service to its customers. At such point, the Company has the sole ability to monetize the third-party publishers advertising inventory. In such transactions, the Company obtains control of a right to a service to be performed by the third-party publishers, which gives the Company the ability to direct those publishers to provide the services to the Company's customers on the Company's behalf. Therefore, the Company reports advertising revenue generated from these transactions on a gross basis and records the related traffic acquisition costs as cost of revenue. Fees for the advertising services above are recognized in the period when advertising is delivered as evidenced by a person engaging with a Promoted Tweet or an ad on a third-party publisher website or application in a manner satisfying the types of engagement selected by the advertisers, such as Tweet engagements (e.g., Retweets, replies and likes), website clicks, mobile application installs or engagements, obtaining new followers, or video views, following a Promoted Account, delivery of impressions, or through the display of a Promoted Trend on the Company's platform. The Company has concluded that its data licensing arrangements, which grant customers a right to its intellectual property (IP) for a defined period of time, may contain a single performance obligation satisfied at a point in time (Historical IP) or over time (Future IP), or may contain two or more performance obligations satisfied separately at a point in time (Historical IP) and over time (Future IP). In some of the Company's data licensing arrangements, pricing is a fixed monthly fee over a specified term. In arrangements with a single performance obligation satisfied over time, data licensing revenue is recognized on a straight-line basis over the period in which the Company provides data as the customer consumes and benefits from the continuous data available on an ongoing basis. In arrangements with at least two performance obligations, the Company allocates revenue on a relative basis between the performance obligations based on standalone selling price (SSP) and recognizes revenue as the performance obligations are satisfied. In other data licensing arrangements, the Company charges customers based on the amount of sales they generate from downstream customers using Twitter data. Certain of those royalty-based data licensing arrangements are subject to minimum guarantees. For such arrangements with a minimum guarantee and a single Future IP performance obligation, the Company recognizes revenue for minimum guarantees on a straight-line basis over the period in which the Company provides data. For such arrangements with a minimum guarantee and two or more performance obligations, the Company allocates revenue on a relative basis between the performance obligations based on SSP and recognizes revenue as the performance obligations are satisfied. Royalties in excess of minimum guarantees, if any, are recognized as revenue over the contract term, on a straight-line, cumulative catch-up basis. This reflects the nature of the Company’s performance obligation, which is a series of distinct monthly periods of providing a license of IP. For data licensing arrangements involving two or more performance obligations, the Company uses directly observable standalone transactions to determine SSP of Historical IP. The Company uses standalone transactions and considers all other reasonably available observable evidence to estimate SSP of Future IP. Other revenue is primarily generated from service fees from transactions completed on the Company's mobile ad exchange. The Company's mobile ad exchange enables buyers and sellers to purchase and sell advertising inventory by matching them in the exchange. The Company has determined it is not the principal in the purchase and sale of advertising inventory in transactions between third-party buyers and sellers on the exchange because the Company does not obtain control of the advertising inventory. The Company reports revenue related to its ad exchange services on a net basis for the fees paid by buyers, net of costs related to acquiring the advertising inventory paid to sellers. Arrangements involving multiple performance obligations primarily consist of combinations of the Company's pay-for-performance products, Promoted Tweets and Promoted Accounts, which are priced through an auction, and Promoted Trends, which are priced on a fixed-fee-per day, per geography basis. For arrangements that include a combination of these products, the Company develops an estimate of the standalone selling price for these products in order to allocate any potential discount to all performance obligations in the arrangement. The estimate of standalone selling price for pay-for-performance auction based products is determined based on the winning bid price. The estimate of standalone selling price for Promoted Trends is based on Promoted Trends sold on a standalone basis and/or separately priced in a bundled arrangement by reference to a list price by geography, which is updated and approved periodically. For other arrangements involving multiple performance obligations where neither auction pricing nor standalone sales provide sufficient evidence of standalone selling price, the Company estimates standalone selling price using either an adjusted market assessment approach or an expected cost plus margin approach. The Company believes the use of its estimation approach and allocation of the transaction price on a relative standalone selling price basis to each performance obligation results in revenue recognition in a manner consistent with the underlying economics of the transaction and the allocation principle included in Topic 606. The Company has elected to exclude certain sales and indirect taxes from the determination of the transaction price. Cost of Revenue Cost of revenue includes infrastructure costs, other direct costs including revenue share expenses, amortization expense of technology acquired through acquisitions and amortization of capitalized labor costs for internally developed software, allocated facilities costs, as well as traffic acquisition costs (TAC). Infrastructure costs consist primarily of data center costs related to the Company’s co-located facilities, which include lease and hosting costs, related support and maintenance costs and energy and bandwidth costs, public cloud hosting costs, as well as depreciation of servers and networking equipment, and personnel-related costs, including salaries, benefits and stock-based compensation, for its operations teams. Revenue share expenses are primarily related to payments to providers from whom the Company licenses content, in order to increase engagement on the platform. The fees paid to these content providers may be based on revenues generated, or a minimum guaranteed fee. TAC consists of costs incurred with third parties in connection with the sale to advertisers of advertising products that the Company places on third-party publishers’ websites, applications or other offerings collectively resulting from acquisitions. Stock-Based Compensation Expense The Company accounts for stock-based compensation expense under the fair value recognition and measurement provisions of GAAP. Stock-based awards granted to employees are measured based on the grant-date fair value. For service-based restricted stock awards and performance-based restricted stock awards, the Company recognizes the compensation expense only for those awards expected to meet the performance and service vesting conditions. For service-based restricted stock awards, expense is recognized on a straight-line basis over the requisite service period. The service condition for restricted stock awards is generally satisfied over four years, but has been up to five years in certain circumstances. For performance-based restricted stock awards, expense is recognized on a graded basis over the requisite service period. For market-based restricted stock awards, the Company recognizes the compensation expense on a graded basis over the requisite service period regardless of whether the market condition is satisfied, provided that the requisite service has been provided. The requisite service period for performance-based and market-based restricted stock awards is generally up to three years. The Company accounts for forfeitures as they occur. The Company estimates the fair value of stock options granted and stock purchase rights provided under the Company’s employee stock purchase plan using the Black-Scholes option pricing model on the dates of grant. The compensation expense related to stock options and employee stock purchase rights is recognized on a straight-line basis over the requisite service period. The fair value of market-based restricted stock awards is determined using a Monte Carlo simulation to estimate the grant date fair value. The Company issues restricted stock subject to a lapsing right of repurchase to continuing employees of certain acquired companies. Since these issuances are subject to post-acquisition employment, the Company accounts for them as post-acquisition stock-based compensation expense. The grant-date fair value of restricted stock granted in connection with acquisitions is recognized as stock-based compensation expense on a straight-line basis over the requisite service period. Business Combinations The Company allocates the purchase price of the acquisition to the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values at the acquisition dates. The excess of the purchase price over those fair values is recorded as goodwill. During the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations. Investments in Privately-Held Companies The Company makes strategic investments in privately-held companies. The Company also evaluates each investee to determine if the investee is a variable interest entity and, if so, whether the Company is the primary beneficiary of the variable interest entity. The Company has determined, as of December 31, 2020, there were no variable interest entities required to be consolidated in the Company’s consolidated financial statements. The Company’s investments in privately-held companies are primarily non-marketable equity securities without readily determinable fair values. The Company accounts for its investments in privately-held companies either under equity method accounting or by adjusting the carrying value of its non-marketable equity securities to fair value upon observable transactions for identical or similar investments of the same issuer or upon impairment (referred to as the measurement alternative). The investments in privately-held companies are included within Other Assets on the consolidated balance sheets. All gains and losses on non-marketable equity securities, realized and unrealized, are recognized in other income (expense), net in the consolidated statements of operations. The Company periodically evaluates the carrying value of the investments in privately-held companies when events and circumstances indicate that the carrying amount of the investment may not be recovered. The Company estimates the fair value of the investments to assess whether impairment losses shall be recorded using Level 3 inputs. These investments include the Company’s holdings in privately-held companies that are not exchange traded and therefore not supported with observable market prices; hence, the Company may determine the fair value by reviewing equity valuation reports, current financial results, long-term plans of the privately-held companies, the amount of cash that the privately-held companies have on-hand, the ability to obtain additional financing and overall market conditions in which the privately-held companies operate or based on the price observed from the most recent completed financing. Loss Contingencies The Company is currently involved in, and may in the future be involved in, legal proceedings, claims, investigations, and government inquiries and investigations arising in the ordinary course of business. The Company records a liability when it believes that it is both probable that a loss has been incurred and the amount or range can be reasonably estimated. If the Company determines there is a reasonable possibility that it may incur a loss and the loss or range of loss can be estimated, it discloses the possible loss to the extent material. Significant judgment is required to determine both probability and the estimated amount. The Company reviews these provisions on a quarterly basis and adjusts these provisions accordingly to reflect the impact of negotiations, settlements, rulings, advice of legal counsel, and updated information. Operating and Finance Leases The Company has operating leases primarily for office space and data center facilities. The determination of whether an arrangement is a lease or contains a lease is made at inception by evaluating whether the arrangement conveys the right to use an identified asset and whether the Company obtains substantially all of the economic benefits from and has the ability to direct the use of the asset. Operating leases are included in operating lease right-of-use assets, operating lease liabilities, short-term, and operating lease liabilities, long-term on the Company’s consolidated balance sheets. With the exception of initial adoption of the new lease standard, where the Company’s incremental borrowing rate used was the rate on the adoption date (January 1, 2019), operating lease ROU assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at the lease commencement date. To determine the incremental borrowing rate used to calculate the present value of future lease payments, the Company uses information including the Company’s credit rating, interest rates of similar debt instruments of entities with comparable credit ratings, the Company's recent debt issuances, and Twitter, Inc.’s guarantee of certain leases in foreign jurisdictions, as applicable. Certain lease agreements contain options for the Company to renew or early terminate a lease. The Company considers these options, which may be elected at the Company’s sole discretion, in determining the lease term on a lease-by-lease basis. Leases with an initial term of twelve months or less are not recognized on the consolidated balance sheets. The Company recognizes lease expense for these leases on a straight-line basis over the term of the lease. The Company also has server and networking equipment lease arrangements with original lease terms ranging from three four The Company’s lease agreements generally do not contain any material residual value guarantees or material restrictive covenants. Certain of the Company’s leases contain free or escalating rent payment terms. Additionally, certain lease agreements contain lease components (for example, fixed payments such as rent) and non-lease components such as common-area maintenance costs. For each asset class of the Company’s leases—real estate offices, data centers, and equipment—the Company has elected to account for both of these provisions as a single lease component. For arrangements accounted for as a single lease component, there may be variability in future lease payments as the amount of the non-lease components is typically revised from one period to the next. These variable lease payments, which are primarily comprised of common-area maintenance, utilities, and real estate taxes that are passed on from the lessor in proportion to the space leased by the Company, are recognized in operating expenses in the period in which the obligation for those payments was incurred. The Company recognizes lease expense for its operating leases in operating expenses on a straight-line basis over the term of the lease. The Company subleases certain leased office space to third parties when it determines there is excess leased capacity. Certain of these subleases contain both lease and non-lease components. The Company has elected to account for both of these provisions as a single lease component. Sublease rent income is recognized as an offset to operating expense on a straight-line basis over the lease term. In addition to sublease rent, variable non-lease costs such as common-area maintenance, utilities, and real estate taxes are charged to subtenants over the duration of the lease for their proportionate share of these costs. These variable non-lease income receipts are recognized in operating expenses as a reduction to costs incurred by the Company in relation to the head lease. Cash, Cash Equivalents and Investments The Company invests its excess cash primarily in short-term fixed income securities, including government and investment-grade debt securities and money market funds. The Company classifies all liquid investments with stated maturities of three months or less from date of purchase as cash equivalents. The Company classifies all marketable securities for use in current operations, even if the security matures beyond 12 months, and presents them as short-term investments in the consolidated balance sheets. As of December 31, 2020 and 2019, the Company has restricted cash balances of $2.3 million and $1.9 million, respectively, within prepaid expenses and other current assets and $20.6 million and $26.7 million, respectively, in other assets on the accompanying consolidated balance sheets based upon the term of the remaining restrictions. These restricted cash balances are primarily cash deposits to back letters of credit related to certain property leases. The Company determines the appropriate classification of its investments in marketable securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company has classified and accounted for its marketable securities as available-for-sale. After considering the Company’s capital preservation objectives, as well as its liquidity requirements, the Company may sell securities prior to their stated maturities. The Company carries its available-for-sale securities at fair value. The Company reports the unrealized gains and losses, net of taxes, as a component of stockholders’ equity, except for unrealized losses determined to be credit-related, which are recorded as other income (expense), net in the consolidated statements of operations and reports an allowance for credit losses in short-term investments on the balance sheet, if any. The Company determines any realized gains or losses on the sale of marketable securities on a specific identification method and records such gains and losses as a component of other income (expense), net. Interest earned on cash, cash equivalents, and marketable securities was $88.2 million, $157.7 million, and $111.2 million during the years ended December 31, 2020, 2019 and 2018, respectively. These amounts are recorded in interest income in the accompanying consolidated statements of operations. The Company's investment policy only allows purchases of investment-grade notes and provides guidelines on concentrations to ensure minimum risk of loss. The Company evaluates whether the unrealized loss on available-for-sale debt securities is the result of the credit worthiness of the corporate notes it held, or other non-credit-related factors such as liquidity by reviewing a number of factors such as the implied yield of the corporate note based on the market price, the nature of the invested entity's business or industry, market capitalization relative to debt, changes in credit ratings, and the market prices of the corporate notes subsequent to period end. As of December 31, 2020, the gross unrealized loss on available-for-sale debt securities was immaterial and there were no expected credit losses related to the Company's available-for-sale debt securities. The Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell these investments before recovery of their amortized cost bases. As of December 31, 2020, no allowance for credit losses in short-term investments was recorded. Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, short-term investments and accounts receivable. The primary focus of the Company’s investment strategy is to preserve capital and meet liquidity requirements. The Company’s investment policy addresses the level of credit exposure by limiting the concentration in any one corporate issuer or sector and establishing a minimum allowable credit rating. To manage the risk exposure, the Company invests cash equivalents and short-term investments in a variety of fixed income securities, including government and investment-grade debt securities and money market funds. The Company places its cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits, if any. The Company’s accounts receivable are typically unsecured and are derived from customers around the world in different industries. The Company includes terms in its contracts providing the ability to stop transferring promised goods or services, performs ongoing credit evaluations of its customers, and maintains allowances for potential credit losses. Historically, such losses have been within management’s expectations. As of December 31, 2020 and 2019, no single customer accounted for more than 10% of the Company’s net accounts receivable balances. No single customer accounted for more than 10% of the Company’s revenue in the years ended December 31, 2020, 2019 and 2018. The Company’s note hedge transactions, entered into in connection with the Convertible Notes, as defined and further described in Note 5 – Fair Value Measurements, and its derivative financial instruments expose the Company to credit risk to the extent that its counterparties may be unable to meet the terms of the transactions. The Company mitigates this risk by limiting its counterparties to major financial institutions and using multiple financial institutions as counterparties in its hedge transactions. Accounts Receivable, Net The Company records accounts receivable at the invoiced amount. The Company maintains an allowance for doubtful accounts to reserve for potentially uncollectible receivable amounts. In evaluating the Company’s ability to collect outstanding receivable balances, the Company considers various factors including the age of the balance, the creditworthiness of the customer, which is assessed based on ongoing credit evaluations and payment history, the customer’s current financial condition, and considers macroeconomic factors to estimate expected future credit losses. In the year ended December 31, 2020, the Company recorded a $17.2 million increment in the allowance for doubtful accounts, offset by $2.7 million of write-offs and other adjustments. Unbilled Revenue (Contract Assets) The Company evaluates whether its unbilled revenue is exposed to potential credit losses by considering factors such as the creditworthiness of its customers, the term over which unbilled revenue will be recognized, historical impairment of unbilled revenue, and contemplation of projected macroeconomic factors. As of December 31, 2020, the Company recorded an immaterial amount of allowance for credit losses on unbilled revenue. Property and Equipment, Net Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life. The estimated useful lives of property and equipment are described below: Property and Equipment Estimated Useful Life Computer hardware, networking and office equipment Three Computer software Up to five Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term The Company reviews the remaining estimated useful lives of its property and equipment on an ongoing basis. Management is required to use judgment in determining the estimated useful lives of such assets. Changes in circumstances such as technological advances, changes to the Company’s business model, changes in the Company’s business strategy, or changes in the planned use of property and equipment could result in the actual useful lives differing from the Company’s current estimates. In cases where the Company determines that the estimated useful life of property and equipment should be shortened or extended, the Company would apply the new estimated useful life prospectively. The Company reviews property and equipment for impairment when events or circumstances indicate the carrying amount may not be recoverable. Costs of maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. Upon retirement or sale, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is reflected in operating expenses. Capitalization of Interest Interest costs are capitalized for assets that are constructed for the Company’s own internal use, including internally developed software and property and equipment, for the period of time to get them ready for their intended use. During the years ended December 31, 2020, 2019 and 2018, the Company capitalized $3.8 million, $4.6 million, and $3.7 million of interest expense, respectively. Goodwill Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired in a business combination. Goodwill is not amortized, but is tested for impairment at least annually or more frequently if events or changes in circumstances indicate that the asset may be impaired. The Company’s impairment tests are based on a single operating segment and reporting unit structure. If the carrying value of the reporting unit exceeds its fair value, an impairment charge is recognized for the excess of the carrying value of the reporting unit over its fair value. The Company conducted its ann

Revenue

Revenue	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Revenue Recognition Revenue is recognized when the control of promised goods or services is transferred to customers at an amount that reflects the consideration to which the Company expects to be entitled to in exchange for those goods or services. The Company identifies its contracts with customers and all performance obligations within those contracts. The Company then determines the transaction price and allocates the transaction price to the performance obligations within the Company's contracts with customers, recognizing revenue when, or as the Company satisfies its performance obligations. While the majority of the Company's revenue transactions are based on standard business terms and conditions, the Company also enters into sales agreements with advertisers and data partners that sometimes involve multiple performance obligations and occasionally include non-standard terms or conditions. Revenue by geography is based on the billing address of the customers. The following tables set forth revenue by services and revenue by geographic area (in thousands): Year Ended December 31, 2020 2019 2018 Revenue by services: Advertising services $ 3,207,392 $ 2,993,392 $ 2,617,397 Data licensing and other 508,957 465,937 424,962 Total revenue $ 3,716,349 $ 3,459,329 $ 3,042,359 Year Ended December 31, 2020 2019 2018 Revenue by geographic area: United States $ 2,078,836 $ 1,944,022 $ 1,642,259 Japan 547,862 537,021 507,970 Rest of World 1,089,651 978,286 892,130 Total revenue $ 3,716,349 $ 3,459,329 $ 3,042,359 Practical Expedients and Exemptions The Company expenses sales commissions as incurred when the amortization period is one year or less. Sales commission expenses are recorded within sales and marketing in the consolidated statements of operations. The Company applied the practical expedient to not disclose the value of remaining performance obligations not yet satisfied as of period end for contracts with an original expected duration of one year or less. Contract Balances The Company enters into contracts with its customers, which may give rise to contract liabilities (deferred revenue) and contract assets (unbilled revenue). The payment terms and conditions within the Company’s contracts vary by the type and location of its customer and products or services purchased, the substantial majority of which are due in less than one year. When the timing of revenue recognition differs from the timing of payments made by customers, the Company recognizes either unbilled revenue (its performance precedes the billing date) or deferred revenue (customer payment is received in advance of performance). Unbilled Revenue (Contract Assets) The Company presents unbilled revenue in the consolidated balance sheets within prepaid expenses and other current assets and within other assets. The Company’s contracts do not contain material financing components. The Company's unbilled revenue primarily consists of amounts that have yet to be billed under contracts with escalating fee structures. Specifically, because the Company generally recognizes revenue on a straight-line basis for data licensing arrangements with escalating fee structures, revenue recognized represents amounts to which the Company is contractually entitled; however, the revenue recognized exceeds the amounts the Company has a right to bill as of the period end, thus resulting in unbilled revenue. Deferred Revenue (Contract Liabilities) The Company presents deferred revenue primarily within accrued and other current liabilities in the consolidated balance sheets and there is not expected to be any material non-current contract liabilities given the Company's contracting provisions. The Company's deferred revenue balance primarily consists of cash payments due in advance of satisfying its performance obligations relating to data licensing contracts and performance obligations given to customers based on their spend relating to advertising contracts, for which the Company defers, as they represent material rights. The Company recognizes deferred revenue relating to its data licensing contracts on a straight-line basis over the period in which the Company provides data. The Company recognizes deferred revenue relating to its advertising contracts based on the amount of customer spend and the relative standalone selling price of the material rights. The following table presents contract balances (in thousands): December 31, December 31, Unbilled Revenue $ 44,063 $ 27,691 Deferred Revenue $ 62,191 $ 69,000 The amount of revenue recognized in the year ended December 31, 2020 that was included in the deferred revenue balance as of December 31, 2019 was $69.0 million. The amount of revenue recognized in the year ended December 31, 2019 that was included in the deferred revenue balance as of December 31, 2018 was $38.9 million. This revenue consists primarily of revenue recognized as a result of the utilization of bonus ads inventory earned by and material rights provided to customers in prior periods and the satisfaction of the Company’s performance obligations relating to data licensing contracts with advance cash payments or material rights. The amount of revenue recognized from obligations satisfied (or partially satisfied) in prior periods was not material. The increase in the unbilled revenue balance from December 31, 2019 to December 31, 2020 was primarily attributable to differences between revenue recognized and amounts billed in the Company's data licensing arrangements with escalating fee structures due to recognizing such fees as revenue on a straight-line basis. The decrease in the deferred revenue balance from December 31, 2019 to December 31, 2020 was primarily due to utilization of bonus and make good ads inventory earned in prior periods and the satisfaction of the Company's performance obligations relating to data licensing contracts with advance cash payments or material rights, offset by bonus ads inventory offered to customers during the period. Remaining Performance Obligations As of December 31, 2020, the aggregate amount of the transaction price allocated to remaining performance obligations in contracts with an original expected duration exceeding one year is $774.4 million. This total amount primarily consists of long-term data licensing contracts and excludes deferred revenue related to the Company’s short-term advertising service arrangements. The Company expects to recognize this amount as revenue over the following time periods (in thousands): Remaining Performance Obligations 2021 2022 2023 and Thereafter Revenue expected to be recognized on remaining performance obligations $ 774,447 $ 299,300 $ 215,794 $ 259,353

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-term Investments	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Short-term Investments	Cash, Cash Equivalents and Short-term Investments Cash, cash equivalents and short-term investments consist of the following (in thousands): December 31, December 31, Cash and cash equivalents: Cash $ 285,002 $ 254,405 Money market funds 1,158,927 465,158 Corporate notes, commercial paper and certificates of deposit 544,500 1,079,519 Total cash and cash equivalents $ 1,988,429 $ 1,799,082 Short-term investments: U.S. government and agency securities $ 910,259 $ 660,860 Corporate notes, commercial paper and certificates of deposit 4,572,394 4,179,110 Marketable equity securities 1,220 — Total short-term investments $ 5,483,873 $ 4,839,970 The contractual maturities of debt securities classified as available-for-sale as of December 31, 2020 were as follows (in thousands): December 31, Due within one year $ 2,733,961 Due after one year through five years 2,748,692 Total $ 5,482,653 The following tables summarize unrealized gains and losses related to available-for-sale debt securities classified as short-term investments on the Company’s consolidated balance sheets (in thousands): December 31, 2020 Gross Gross Gross Aggregated U.S. government and agency securities $ 909,092 $ 1,177 $ (10) $ 910,259 Corporate notes, commercial paper and certificates of deposit 4,545,687 26,939 (232) 4,572,394 Total available-for-sale debt securities classified as short-term investments $ 5,454,779 $ 28,116 $ (242) $ 5,482,653 December 31, 2019 Gross Gross Gross Aggregated U.S. government and agency securities $ 660,361 $ 1,049 $ (550) $ 660,860 Corporate notes, commercial paper and certificates of deposit 4,166,203 13,133 (226) 4,179,110 Total available-for-sale debt securities classified as short-term investments $ 4,826,564 $ 14,182 $ (776) $ 4,839,970 The available-for-sale debt securities classified as cash and cash equivalents on the consolidated balance sheets are not included in the tables above as the gross unrealized gains and losses were immaterial for each period. Their carrying value approximates fair value because of the short maturity period of these instruments.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value MeasurementsThe Company measures its cash equivalents, short-term investments and derivative financial instruments at fair value. The Company classifies its cash equivalents, short-term investments and derivative financial instruments within Level 1 or Level 2 because the Company values these investments using quoted market prices or alternative pricing sources and models utilizing market observable inputs. The fair value of the Company’s Level 1 financial assets is based on quoted market prices of the identical underlying security. The fair value of the Company’s Level 2 financial assets is based on inputs that are directly or indirectly observable in the market, including the readily-available pricing sources for the identical underlying security that may not be actively traded. The following tables set forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019 based on the three-tier fair value hierarchy (in thousands): December 31, 2020 Level 1 Level 2 Total Assets Cash equivalents: Money market funds $ 1,158,927 $ — $ 1,158,927 Corporate notes — 1,347 1,347 Commercial paper — 543,153 543,153 Short-term investments: U.S. government and agency securities — 910,259 910,259 Corporate notes — 2,829,521 2,829,521 Commercial paper — 1,240,670 1,240,670 Certificates of deposit — 502,203 502,203 Marketable equity securities 1,220 — 1,220 Other current assets: Foreign currency contracts — 5,529 5,529 Total $ 1,160,147 $ 6,032,682 $ 7,192,829 Liabilities Other current liabilities: Foreign currency contracts $ — $ 1,028 $ 1,028 Total $ — $ 1,028 $ 1,028 December 31, 2019 Level 1 Level 2 Total Assets Cash equivalents: Money market funds $ 465,158 $ — $ 465,158 Corporate notes — 8,246 8,246 Commercial paper — 1,031,825 1,031,825 Certificates of deposit — 39,448 39,448 Short-term investments: U.S. government and agency securities — 660,860 660,860 Corporate notes — 2,468,429 2,468,429 Commercial paper — 1,236,487 1,236,487 Certificates of deposit — 474,194 474,194 Other current assets: Foreign currency contracts — 3,756 3,756 Total $ 465,158 $ 5,923,245 $ 6,388,403 Liabilities Other current liabilities: Foreign currency contracts $ — $ 1,573 $ 1,573 Total $ — $ 1,573 $ 1,573 The Company has $954.0 million in aggregate principal amount of 1.00% convertible senior notes due in 2021, or the 2021 Notes, $1.15 billion in aggregate principal amount of 0.25% convertible senior notes due in 2024, or the 2024 Notes, $1.0 billion in aggregate principal amount of 0.375% convertible senior notes due in 2025, or the 2025 Notes, and, taken together with the 2021 Notes and the 2024 Notes, the Convertible Notes. The Company also has $700.0 million in aggregate principal amount of 3.875% senior notes due in 2027, or the 2027 Notes, and, together with the Convertible Notes, the Notes, outstanding as of December 31, 2020. Refer to Note 11 – Senior Notes and Convertible Notes for further details on the Notes. The estimated fair value of the 2021 Notes, the 2024 Notes, and the 2027 Notes, based on a market approach as of December 31, 2020 was approximately $975.3 million, $1.39 billion, and $745.5 million, respectively, which represents a Level 2 valuation. The estimated fair value was determined based on the estimated or actual bids and offers of the Notes in an over-the-counter market on the last business day of the period. The estimated fair value of the 2025 Notes, based on a binomial model, as of December 31, 2020 was approximately $1.45 billion, which represents a Level 3 valuation. The Level 3 inputs used include risk free rate, volatility and discount yield. Derivative Financial Instruments The Company enters into foreign currency forward contracts with financial institutions to reduce the risk that its earnings may be adversely affected by the impact of exchange rate fluctuations on monetary assets or liabilities denominated in currencies other than the functional currency of a subsidiary. These contracts do not subject the Company to material balance sheet risk due to exchange rate movements because gains and losses on these derivatives are intended to offset gains and losses on the hedged foreign currency denominated assets and liabilities. These foreign currency forward contracts are not designated as hedging instruments. The Company recognizes these derivative instruments as either assets or liabilities in the consolidated balance sheets at fair value based on a Level 2 valuation. The Company records changes in the fair value (i.e., gains or losses) of the derivatives in other income (expense), net in the consolidated statements of operations. The notional principal of foreign currency contracts outstanding was equivalent to $729.8 million and $456.1 million at December 31, 2020 and 2019, respectively. The fair values of outstanding derivative instruments for the periods presented on a gross basis are as follows (in thousands): Balance Sheet Location December 31, December 31, Assets Foreign currency contracts not designated as hedging instruments Other current assets $ 5,529 $ 3,756 Liabilities Foreign currency contracts not designated as hedging instruments Other current liabilities $ 1,028 $ 1,573

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net The following tables set forth property and equipment, net by type and by geographic area for the periods presented (in thousands): December 31, December 31, Property and equipment, net Equipment $ 1,830,459 $ 1,445,003 Furniture and leasehold improvements 362,766 347,983 Capitalized software 811,371 688,894 Construction in progress 349,935 100,551 Total 3,354,531 2,582,431 Less: Accumulated depreciation and amortization (1,860,737) (1,550,650) Property and equipment, net $ 1,493,794 $ 1,031,781 December 31, December 31, Property and equipment, net: United States $ 1,460,163 $ 999,552 International 33,631 32,229 Total property and equipment, net $ 1,493,794 $ 1,031,781 Depreciation expense totaled $471.6 million, $449.0 million, and $406.5 million for the years ended December 31, 2020, 2019 and 2018, respectively. Included in these amounts were depreciation expense for server and networking equipment acquired under finance leases in the amount of $20.5 million, $63.7 million, and $84.2 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Operating and Finance Leases

Operating and Finance Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Operating and Finance Leases	Operating and Finance Leases The Company’s leases have remaining lease terms from less than one year up to approximately ten years. As of December 31, 2020 and 2019, assets recorded under finance leases were $13.3 million and $126.0 million, respectively, and accumulated depreciation associated with finance leases was $12.8 million and $104.2 million, respectively, recorded in property and equipment, net on the consolidated balance sheets. The components of lease cost for the year ended December 31, 2020 were as follows (in thousands): Year Ended December 31, 2020 2019 Operating lease cost $ 201,386 $ 173,005 Finance lease cost Depreciation expense 20,527 63,674 Interest on lease liabilities 369 2,125 Total finance lease cost 20,896 65,799 Short-term lease cost 5,603 3,000 Variable lease cost 52,476 49,456 Sublease income (9,626) (22,326) Total lease cost $ 270,735 $ 268,934 Other information related to leases was as follows (in thousands): Year Ended December 31, 2020 2019 Supplemental Cash Flows Information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 183,033 $ 165,093 Operating cash flows from finance leases $ 369 $ 2,125 Financing cash flows from finance leases $ 23,062 $ 66,677 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 398,480 $ 110,522 December 31, December 31, Lease Term and Discount Rate Weighted-average remaining lease term (years): Operating leases 6.8 6.6 Finance leases 0.1 0.7 Weighted-average discount rate: Operating leases 3.8 % 4.3 % Finance leases 3.9 % 3.7 % Future lease payments under leases and sublease income as of December 31, 2020 were as follows (in thousands): Operating Finance Total Sublease Year Ending December 31, 2021 $ 218,869 $ 569 $ 219,438 $ (8,976) 2022 251,548 — 251,548 (1,353) 2023 178,870 — 178,870 — 2024 178,669 — 178,669 — 2025 175,585 — 175,585 — Thereafter 667,742 — 667,742 — Total future lease payments (receipts) 1,671,283 569 1,671,852 $ (10,329) Less: leases not yet commenced (528,964) — (528,964) Less: imputed interest (145,424) (2) (145,426) Total lease liabilities $ 996,895 $ 567 $ 997,462 Reconciliation of lease liabilities as shown in the consolidated balance sheets Operating lease liabilities, short-term $ 177,147 $ — $ 177,147 Operating lease liabilities, long-term 819,748 — 819,748 Finance lease liabilities, short-term — 567 567 Total lease liabilities $ 996,895 $ 567 $ 997,462
Operating and Finance Leases	Operating and Finance Leases The Company’s leases have remaining lease terms from less than one year up to approximately ten years. As of December 31, 2020 and 2019, assets recorded under finance leases were $13.3 million and $126.0 million, respectively, and accumulated depreciation associated with finance leases was $12.8 million and $104.2 million, respectively, recorded in property and equipment, net on the consolidated balance sheets. The components of lease cost for the year ended December 31, 2020 were as follows (in thousands): Year Ended December 31, 2020 2019 Operating lease cost $ 201,386 $ 173,005 Finance lease cost Depreciation expense 20,527 63,674 Interest on lease liabilities 369 2,125 Total finance lease cost 20,896 65,799 Short-term lease cost 5,603 3,000 Variable lease cost 52,476 49,456 Sublease income (9,626) (22,326) Total lease cost $ 270,735 $ 268,934 Other information related to leases was as follows (in thousands): Year Ended December 31, 2020 2019 Supplemental Cash Flows Information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 183,033 $ 165,093 Operating cash flows from finance leases $ 369 $ 2,125 Financing cash flows from finance leases $ 23,062 $ 66,677 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 398,480 $ 110,522 December 31, December 31, Lease Term and Discount Rate Weighted-average remaining lease term (years): Operating leases 6.8 6.6 Finance leases 0.1 0.7 Weighted-average discount rate: Operating leases 3.8 % 4.3 % Finance leases 3.9 % 3.7 % Future lease payments under leases and sublease income as of December 31, 2020 were as follows (in thousands): Operating Finance Total Sublease Year Ending December 31, 2021 $ 218,869 $ 569 $ 219,438 $ (8,976) 2022 251,548 — 251,548 (1,353) 2023 178,870 — 178,870 — 2024 178,669 — 178,669 — 2025 175,585 — 175,585 — Thereafter 667,742 — 667,742 — Total future lease payments (receipts) 1,671,283 569 1,671,852 $ (10,329) Less: leases not yet commenced (528,964) — (528,964) Less: imputed interest (145,424) (2) (145,426) Total lease liabilities $ 996,895 $ 567 $ 997,462 Reconciliation of lease liabilities as shown in the consolidated balance sheets Operating lease liabilities, short-term $ 177,147 $ — $ 177,147 Operating lease liabilities, long-term 819,748 — 819,748 Finance lease liabilities, short-term — 567 567 Total lease liabilities $ 996,895 $ 567 $ 997,462

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following table presents the goodwill activities for the periods presented (in thousands): Goodwill Balance as of December 31, 2019 $ 1,256,699 Acquisitions 50,970 Other 4,677 Balance as of December 31, 2020 $ 1,312,346 For each of the periods presented, gross goodwill balance equaled the net balance since no impairment charges have been recorded. The following table presents the detail of intangible assets for the periods presented (in thousands): Gross Carrying Accumulated Net Carrying December 31, 2020: Patents and developed technologies $ 110,153 $ (53,265) $ 56,888 Other 1,800 (350) 1,450 Total $ 111,953 $ (53,615) $ 58,338 December 31, 2019: Patents and developed technologies $ 96,636 $ (41,530) $ 55,106 Total $ 96,636 $ (41,530) $ 55,106 Patents and developed technologies are amortized over a period of up to eleven years from the respective purchase dates. Amortization expense associated with intangible assets for the years ended December 31, 2020, 2019 and 2018 was $23.6 million, $16.5 million and $19.0 million, respectively. During the year ended December 31, 2020, $11.5 million in gross carrying value and accumulated amortization related to fully-amortized intangible assets was eliminated. Estimated future amortization expense as of December 31, 2020 is as follows (in thousands): 2021 $ 21,583 2022 14,528 2023 7,843 2024 6,026 2025 1,863 Thereafter 6,495 Total $ 58,338

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued and Other Current Liabilities	Accrued and other current liabilities The following table presents the detail of accrued and other current liabilities for the periods presented (in thousands): December 31, December 31, Accrued compensation $ 171,681 $ 190,465 Federal Trade Commission accrual (see Note 16) 150,000 — Deferred revenue 58,976 68,987 Accrued publisher, content and ad network costs 42,541 45,265 Accrued tax liabilities 40,384 45,967 Accrued professional services 27,404 38,596 Accrued other 171,979 111,613 Total $ 662,965 $ 500,893

Acquisitions and Other Investme

Acquisitions and Other Investments	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Acquisitions and Other Investments	Acquisitions and Other Investments 2020 Acquisitions During the year ended December 31, 2020, the Company made a number of acquisitions, which were accounted for as business combinations. The total purchase price for these acquisitions was $69.7 million, which was allocated as follows: $13.8 million to developed technologies and other acquired intangible assets, $4.9 million to net assets assumed based on their estimated fair value on the acquisition date, and the excess $51.0 million of the purchase price over the fair value of net assets acquired to goodwill. The goodwill from the acquisitions is mainly attributable to assembled workforce, expected synergies and other benefits. The goodwill is not tax deductible. Developed technologies and other acquired intangible assets will be amortized on a straight-line basis over their estimated useful lives of up to three years. The results of operations for these acquisitions have been included in the Company’s consolidated statements of operations since the date of each respective acquisition. Actual and pro forma revenue and results of operations for these acquisitions have not been presented because they do not have a material impact on the consolidated results of operations. 2019 Acquisitions During the year ended December 31, 2019, the Company made a number of acquisitions, which were accounted for as business combinations. The total purchase price of $34.5 million (paid in cash of $29.9 million and indemnification holdback of $4.6 million) for these acquisitions was allocated as follows: $9.0 million to developed technology, $1.9 million to net liabilities assumed based on their estimated fair value on the acquisition date, and the excess $27.4 million of the purchase price over the fair value of net assets acquired to goodwill. The goodwill from the acquisitions are mainly attributable to assembled workforce, expected synergies and other benefits. The goodwill is not tax deductible. Developed technologies are amortized on a straight-line basis over their estimated useful lives of up to three years. The results of operations for these acquisitions have been included in the Company’s consolidated statements of operations since the date of acquisition. Actual and pro forma revenue and results of operations for these acquisitions have not been presented because they do not have a material impact on the consolidated results of operations. 2018 Acquisition During the year ended 2018, the Company acquired a company, which was accounted for as a business combination. The purchase price of $53.7 million (paid in shares of the Company’s common stock having a total fair value of $19.1 million and cash of $34.6 million) for this acquisition was allocated as follows: $9.3 million to developed technology, $0.4 million to net tangible assets acquired based on their estimated fair value on the acquisition date, and the excess $44.0 million of the purchase price over the fair value of net assets acquired to goodwill. The goodwill from the acquisition is mainly attributable to assembled workforce, expected synergies and other benefits. The goodwill is not tax deductible for U.S. income tax purposes. The developed technology is amortized on a straight-line basis over its estimated useful life of two years. The results of operations for this acquisition have been included in the Company’s consolidated statements of operations since the date of acquisition. Actual and pro forma revenue and results of operations for this acquisition have not been presented because they do not have a material impact on the consolidated results of operations. Investments in Privately-Held Companies The Company makes strategic investments in privately-held companies that primarily consist of non-marketable equity securities without readily determinable fair values. The Company’s non-marketable equity securities had a combined carrying value of $85.8 million and $77.7 million as of December 31, 2020 and 2019, respectively. As of December 31, 2020, the Company committed to provide up to $60.0 million of bridge financing to one of its investments in privately-held companies. The loan contains a conversion feature where the Company may convert all or any part of the outstanding loan into preference shares through June 30, 2021. No amount was funded as of December 31, 2020. The maximum loss the Company can incur for its investments is their carrying value and any future funding commitments. The Company periodically evaluates the carrying value of the investments in privately-held companies when events and circumstances indicate that the carrying amount of the investment may not be recovered. In the years ended December 31, 2020, 2019 and 2018, the Company recorded $8.8 million, $1.6 million, and $3.0 million of impairment charges, respectively, within other income (expense), net in the consolidated statements of operations. The Company also recorded a gain of $10.2 million from the sale of an investment in a privately-held company in the year ended December 31, 2019 within other income (expense), net in the consolidated statements of operations. No such gains were recorded in the years ended December 31, 2020 and 2018.

Senior Notes and Convertible No

Senior Notes and Convertible Notes	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Senior Notes and Convertible Notes	Senior Notes and Convertible Notes Senior Notes 2027 Notes In 2019, the Company issued $700.0 million aggregate principal amount of the 3.875% senior notes due 2027, or the 2027 Notes, in a private placement to qualified institutional buyers pursuant to Rule144A under the Securities Act of 1933, as amended, and outside the United States pursuant to Regulation S under the Securities Act of 1933. The total net proceeds from this offering were approximately $691.9 million, after deducting $8.1 million of debt issuance costs in connection with the issuance of the 2027 Notes. The 2027 Notes represent senior unsecured obligations of the Company. The interest rate is fixed at 3.875% per annum and interest is payable semi-annually in arrears on June 15 and December 15 of each year, which commenced on June 15, 2020. The 2027 Notes mature on December 15, 2027. The Company may redeem the 2027 Notes, in whole or in part, at any time prior to September 15, 2027 at a price equal to 100% of the principal amount of the 2027 Notes plus a “make-whole” premium and accrued and unpaid interest, if any. On and after September 15, 2027, the Company may redeem the 2027 Notes at 100% of the principal amount plus accrued and unpaid interest, if any, to, but excluding, the redemption date. If the Company experiences a change of control triggering event (as defined in the Indenture), the Company must offer to repurchase the 2027 Notes at a repurchase price equal to 101% of the principal amount of the 2027 Notes to be repurchased, plus accrued and unpaid interest, if any, to the applicable repurchase date. Convertible Notes 2025 Notes In March 2020, the Company entered into an investment agreement (the Investment Agreement) with Silver Lake Partners V DE (AIV), L.P. (Silver Lake) relating to the issuance and sale to Silver Lake of $1.0 billion in aggregate principal amount of the Company's 0.375% convertible senior notes due 2025, or the 2025 Notes. The total net proceeds from this offering were approximately $985.3 million, after deducting $14.7 million of debt issuance costs in connection with the 2025 Notes. The 2025 Notes represent senior unsecured obligations of the Company. The interest rate is fixed at 0.375% per annum and interest is payable semi-annually in arrears on March 15 and September 15 of each year, which commenced on September 15, 2020. The 2025 Notes mature on March 15, 2025, subject to earlier conversion, redemption or repurchase. The 2025 Notes are convertible at the option of the holder at any time until the scheduled trading day prior to the maturity date, including in connection with a redemption by the Company. The 2025 Notes will be convertible into shares of the Company’s common stock based on an initial conversion rate of 24.0964 shares of common stock per $1,000 principal amount of the 2025 Notes, which is equal to an initial conversion price of $41.50 per share, subject to customary anti-dilution and other adjustments, including in connection with any make-whole adjustment as a result of certain extraordinary transactions. Upon conversion of the 2025 Notes, the Company will pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election. If the Company satisfies its conversion obligation solely in cash or through payment and delivery, as the case may be, of a combination of cash and shares of its common stock, the amount of cash and shares of common stock, if any, due upon conversion will be based on a daily conversion value (as set forth in the indenture governing the 2025 Notes) calculated on a proportionate basis for each trading day in a 30 trading day observation period. On or after March 20, 2022, the 2025 Notes will be redeemable by the Company in the event that the closing sale price of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day immediately preceding the date on which the Company provides the redemption notice at a redemption price of 100% of the principal amount of such 2025 Notes, plus accrued and unpaid interest to, but excluding, the redemption date. With certain exceptions, upon a change of control of the Company or a fundamental change (as defined in the indenture governing the 2025 Notes), the holders of the 2025 Notes may require that the Company repurchase all or part of the principal amount of the 2025 Notes at a repurchase price equal to 100% of the principal amount of the 2025 Notes, plus any accrued and unpaid interest to, but excluding, the repurchase date. Pursuant to the Investment Agreement, and subject to certain exceptions, Silver Lake will be restricted from transferring or entering into an agreement that transfers the economic consequences of ownership of the 2025 Notes or converting the 2025 Notes prior to the earlier of (i) the two year anniversary of the original issue date of the 2025 Notes or (ii) immediately prior to the consummation of a change of control of the Company. Exceptions to such restrictions on transfer include, among others: (a) transfers to affiliates of Silver Lake, (b) transfers to the Company or any of its subsidiaries, (c) transfers to a third party where the net proceeds of such sale are solely used to satisfy a margin call or repay a permitted loan or (d) transfers in connection with certain merger and acquisition events. In accordance with the current accounting guidance on convertible debt that may be settled in cash on conversion, the Company separated the conversion option associated with the 2025 Notes (the equity component) from the respective debt instrument (the liability component). The carrying value of the liability component was determined by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying value of the equity component of $121.4 million, which is recognized in stockholders’ equity, represents the difference between the proceeds from the issuance of the 2025 Notes and the fair value of the liability component. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount (the debt discount) is amortized to interest expense at an effective interest rate of 2.99% over the expected life of the 2025 Notes. The Company allocated $1.8 million of issuance costs to the equity component and the remaining issuance costs of $12.9 million are amortized to interest expense under the effective interest rate method over the expected life of the notes. 2021 Notes and 2024 Notes In 2014, the Company issued $954.0 million in aggregate principal amount of the 1.00% convertible senior notes due 2021, or the 2021 Notes, in a private placement to qualified institutional buyers pursuant to Rule 144A of the Securities Act of 1933, as amended. The total net proceeds from this offering were approximately $939.5 million, after deducting $14.3 million of debt discount and $0.2 million of debt issuance costs in connection with the issuance of the 2021 Notes. In 2018, the Company issued $1.15 billion aggregate principal amount of the 0.25% convertible senior notes due 2024, or the 2024 Notes, in a private placement to qualified institutional buyers pursuant to Rule144A under the Securities Act of 1933. The total net proceeds from this offering were approximately $1.14 billion, after deducting $12.3 million of debt issuance costs in connection with the 2024 Notes. The 2021 Notes and the 2024 Notes are senior unsecured obligations of the Company. The interest rate of the 2021 Notes is fixed at 1.00% per annum and interest is payable semi-annually in arrears on March 15 and September 15 of each year. The interest rate of the 2024 Notes is fixed at 0.25% per annum and interest is payable semi-annually in arrears on June 15 and December 15 of each year. The 2021 Notes mature on September 15, 2021 and the 2024 Notes mature on June 15, 2024. Each $1,000 of principal of the 2021 Notes and the 2024 Notes will initially be convertible into 12.8793 and 17.5001 shares, respectively, of the Company’s common stock, which is equivalent to an initial conversion price of approximately $77.64 and $57.14 per share, respectively, in each case, subject to adjustment upon the occurrence of specified events set forth in the indenture governing such series. Holders of the 2021 Notes may convert their 2021 Notes at their option at any time on or after March 15, 2021 until close of business on the second scheduled trading day immediately preceding the maturity date of September 15, 2021. Holders of the 2024 Notes may convert their 2024 Notes at their option at any time on or after March 15, 2024 until close of business on the second scheduled trading day immediately preceding the maturity date of June 15, 2024. Further, holders of the Convertible Notes may convert all or any portion of the notes of the applicable series at the option of such holder prior to March 15, 2021 and March 15, 2024 for the 2021 Notes and 2024 Notes, respectively, only under the following circumstances: 1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2014, in the case of the 2021 Notes, and September 30, 2018, in the case of the 2024 Notes (and, in each case, only during such calendar quarter), if the last reported sale price of the common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the applicable series of Convertible Notes on each applicable trading day; 2) during the five business day period after any five consecutive trading day period (the measurement period) in which the trading price (as defined in the indenture governing the applicable series of Convertible Notes) per $1,000 principal amount of such series of Convertible Notes for each trading day of the applicable measurement period was less than 98% of the product of the last reported sale price of Twitter’s common stock and the conversion rate for the applicable series of Convertible Notes on each such trading day; or 3) upon the occurrence of certain specified corporate events. Upon conversion of the 2021 Notes and 2024 Notes, the Company will pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election. If the Company satisfies its conversion obligation solely in cash or through payment and delivery, as the case may be, of a combination of cash and shares of its common stock, the amount of cash and shares of common stock, if any, due upon conversion of the 2021 Notes or the 2024 Notes, as applicable, will be based on a daily conversion value (as defined in the indenture governing the applicable series of Convertible Notes) calculated on a proportionate basis for each trading day in the applicable 30 trading day observation period. If a fundamental change (as defined in the indenture governing the applicable series of Convertible Notes) occurs prior to the applicable maturity date, holders of the 2021 Notes and 2024 Notes, as applicable, may require the Company to repurchase all or a portion of their notes for cash at a repurchase price equal to 100% of the principal amount of such notes, plus any accrued and unpaid interest to, but excluding, the repurchase date of such series of notes. In addition, if specific corporate events occur prior to the applicable maturity date of the 2021 Notes or the 2024 Notes, the Company will be required to increase the conversion rate for holders who elect to convert their notes in connection with such corporate events. In accordance with accounting guidance on embedded conversion features, the Company valued and bifurcated the conversion option associated with the 2021 Notes and the 2024 Notes from the respective host debt instrument, which is referred to as debt discount, and initially recorded the conversion option of $283.3 million for the 2021 Notes and $255.0 million for the 2024 Notes in stockholders’ equity. The resulting debt discount on the 2021 Notes and the 2024 Notes is amortized to interest expense at an effective interest rate of 6.25% and 4.46%, respectively, over the contractual terms of these notes. The Company allocated $2.8 million of debt issuance costs to the equity component and the remaining $9.8 million of debt issuance costs are amortized to interest expense under the effective interest rate method over the contractual terms of these notes. Concurrent with the offering of the 2021 Notes in 2014 and the 2024 Notes in 2018, the Company entered into convertible note hedge transactions with certain bank counterparties whereby the Company has the option to purchase initially (subject to adjustment for certain specified events) a total of approximately 12.3 million and 20.1 million shares, respectively, of its common stock at a price of approximately $77.64 and $57.14 per share, respectively. The total cost of the convertible note hedge transactions was $233.5 million and $268.0 million, respectively. In addition, the Company sold warrants to certain bank counterparties whereby the holders of the warrants have the option to purchase initially (subject to adjustment for certain specified events) a total of approximately 12.3 million and 20.1 million shares, respectively, of the Company’s common stock at an initial strike price of $105.28 and $80.20 per share, respectively. The Company received $172.9 million and $186.8 million in cash proceeds from the sale of these warrants, respectively. Taken together, the purchase of the convertible note hedges and the sale of warrants in connection with the issuance of the Convertible Notes are intended to offset any actual dilution from the conversion of such notes and to effectively increase the overall conversion price from $77.64 to $105.28 per share, in the case of the 2021 Notes, and from $57.14 to $80.20 per share, in the case of the 2024 Notes. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital in the consolidated balance sheet as of December 31, 2020. Senior Notes and Convertible Notes The Notes consisted of the following (in thousands): December 31, 2020 December 31, 2019 2021 Notes 2024 Notes 2025 Notes 2027 Notes 2021 Notes 2024 Notes 2027 Notes Principal amounts: Principal $ 954,000 $ 1,150,000 $ 1,000,000 $ 700,000 $ 954,000 $ 1,150,000 $ 700,000 Unamortized debt discount and issuance costs (1) (36,134) (160,297) (113,825) (7,006) (84,652) (202,515) (8,033) Net carrying amount $ 917,866 $ 989,703 $ 886,175 $ 692,994 $ 869,348 $ 947,485 $ 691,967 Carrying amount of the equity component (2) $ 283,283 $ 254,981 $ 121,413 $ — $ 283,283 $ 254,981 $ — (1) Included in the consolidated balance sheets within convertible notes, short-term; convertible notes, long-term; and senior notes, long-term, and amortized over the remaining lives of the Notes. (2) Included in the consolidated balance sheets within additional paid-in capital. During the years ended December 31, 2020, 2019, and 2018, the Company recognized $112.2 million, $123.6 million and $115.4 million, respectively, of interest expense related to the amortization of debt discount and issuance costs prior to capitalization of interest. The Company recognized $42.6 million, $15.7 million, and $13.4 million of coupon interest expense in the years ended December 31, 2020, 2019, and 2018, respectively. As of December 31, 2020, the remaining life of the 2021 Notes, the 2024 Notes, the 2025 Notes, and the 2027 Notes is approximately 8 months, 41 months, 50 months, and 83 months, respectively.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income (Loss) per Share Basic net income (loss) per share is computed by dividing net income (loss) attributable to common stockholders by the weighted-average common shares outstanding during the period. The weighted-average common shares outstanding is adjusted for shares subject to repurchase such as unvested restricted stock granted to employees in connection with acquisitions, contingently returnable shares and escrowed shares supporting indemnification obligations that are issued in connection with acquisitions and unvested stock options exercised. Diluted net income (loss) per share is computed by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding during the period, including potential dilutive common stock instruments. In the year ended December 31, 2020, the Company’s potential common stock instruments such as stock options, RSUs, shares to be purchased under the 2013 Employee Stock Purchase Plan, shares subject to repurchases, the conversion feature of the Convertible Notes and the warrants were not included in the computation of diluted loss per share as the effect of including these shares in the calculation would have been anti-dilutive. The following table presents the calculation of basic and diluted net income (loss) per share for periods presented (in thousands, except per share data). Year Ended December 31, 2020 2019 2018 Basic net income (loss) per share: Numerator Net income (loss) $ (1,135,626) $ 1,465,659 $ 1,205,596 Denominator Weighted-average common shares outstanding 789,887 772,663 756,916 Weighted-average restricted stock subject to repurchase (2,026) (1,934) (2,590) Weighted-average shares used to compute basic net income (loss) per share 787,861 770,729 754,326 Basic net income (loss) per share attributable to common stockholders $ (1.44) $ 1.90 $ 1.60 Diluted net income (loss) per share: Numerator Net income (loss) $ (1,135,626) $ 1,465,659 $ 1,205,596 Denominator Number of shares used in basic computation 787,861 770,729 754,326 Weighted-average effect of dilutive securities: RSUs — 10,468 13,285 Stock options — 2,496 2,686 Other — 1,838 2,389 Weighted-average shares used to compute diluted net income (loss) per share 787,861 785,531 772,686 Diluted net income (loss) per share attributable to common stockholders $ (1.44) $ 1.87 $ 1.56 The following potential common shares at the end of each period were excluded from the calculation of diluted net income (loss) per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 RSUs 36,611 12,117 14,949 Warrants 32,412 42,246 44,454 Stock options 1,436 3 837 Shares subject to repurchase and others 5,668 1,284 1,951 Since the Company expects to settle the principal amount of the outstanding Convertible Notes in cash, the Company uses the treasury stock method for calculating any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. For the 2021 Notes, the conversion spread of 12.3 million shares will have a dilutive impact on diluted net income per share of common stock when the average market price of the Company’s common stock for a given period exceeds the conversion price of $77.64 per share. For the 2024 Notes, the conversion spread of 20.1 million shares will have a dilutive impact on diluted net income per share of common stock when the average market price of the Company’s common stock for a given period exceeds the conversion price of $57.14 per share. For the 2025 Notes, the conversion spread of 24.1 million shares will have a dilutive impact on diluted net income per share of common stock when the average market price of the Company's common stock for a given period exceeds the conversion price of $41.50 per share. Since the average market price of the common stock is below the conversion price for all convertible notes for all periods presented, the Convertible Notes are anti-dilutive. If the average market price of the common stock exceeds the exercise price of the warrants, $105.28 for the 2021 Notes, and $80.20 for the 2024 Notes, the warrants will have a dilutive effect on the earnings per share assuming that the Company is profitable. Since the average market price of the common stock is below $80.20 for all periods presented, the warrants are anti-dilutive.

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Preferred Stock	Preferred StockThe Company has the authority to issue up to 200,000,000 shares of preferred stock and to determine the price, rights, preferences, privileges and restrictions, including voting rights, of those shares without any further vote or action by the stockholders. As of December 31, 2020 and 2019, there was no preferred stock outstanding.

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Common Stock and Stockholders' Equity	Common Stock and Stockholders’ Equity Common Stock As of December 31, 2020, the Company is authorized to issue 5.0 billion shares of $0.000005 par value common stock in accordance with the Certificate of Incorporation, as amended and restated. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when and if declared by the Board of Directors, subject to the prior rights of holders of all classes of stock outstanding. As of December 31, 2020, no dividends have been declared. Equity Incentive Plans The Company’s 2013 Equity Incentive Plan serves as the successor to the 2007 Equity Incentive Plan. Initially, 68.3 million shares were reserved under the 2013 Equity Incentive Plan and any shares subject to options or other similar awards granted under the 2007 Equity Incentive Plan that expire, are forfeited, are repurchased by the Company or otherwise terminate unexercised will become available under the 2013 Equity Incentive Plan. The number of shares of the Company’s common stock available for issuance under the 2013 Equity Incentive Plan were and will be increased on the first day of each fiscal year beginning with the 2014 fiscal year, in an amount equal to the least of (i) 60,000,000 Shares, (ii) 5% of the outstanding Shares on the last day of the immediately preceding fiscal year or (iii) such number of Shares determined by the Company’s Board of Directors. As of December 31, 2020, the total number of options, RSUs, and PRSUs outstanding under the 2013 Equity Incentive Plan was 38.6 million shares, and 217.9 million shares were available for future issuance. There were 0.5 million shares of options outstanding under the 2007 Equity Incentive Plan as of December 31, 2020. No additional shares have been issued under the 2007 Equity Incentive Plan since 2013. In addition, a total of 6.8 million shares were reserved and are available for grants under the Company's 2016 Equity Incentive Plan. As of December 31, 2020, no shares have been issued under the 2016 Equity Incentive Plan. Options granted under the Company’s Equity Incentive Plans generally expire 10 years after the grant date. The Company issues new shares to satisfy stock option exercises. The Company also assumed stock options of acquired entities in connection with certain acquisitions. While the respective stock plans were terminated on the closing of each acquisition, they continue to govern the terms of stock options assumed in the respective acquisition. Share Repurchases In March 2020, the Company's Board of Directors authorized a program to repurchase up to $2.0 billion of the Company's common stock over time. Repurchases may be made from time to time through open market purchases or through privately negotiated transactions subject to market conditions, applicable legal requirements and other relevant factors. The repurchase program does not obligate the Company to acquire any particular amount of its common stock, and may be suspended at any time at the Company’s discretion. In the year ended December 31, 2020, the Company repurchased 5.7 million shares for an aggregate amount of $250.6 million, including 98,000 shares for $5.3 million that were not settled as of December 31, 2020 that are presented as treasury stock on the consolidated balance sheets, under the program. Restricted Common Stock The Company has granted restricted common stock to certain continuing employees in connection with the acquisitions. Vesting of this stock is dependent on the respective employee’s continued employment at the Company during the requisite service period, which is up to four years from the issuance date, and the Company has the right to repurchase the unvested shares upon termination of employment. The fair value of the restricted common stock issued to employees is recorded as compensation expense on a straight-line basis over the requisite service period. The activities for the restricted common stock issued to employees for the year ended December 31, 2020 are summarized as follows (in thousands, except per share data): Number of Weighted-Average Unvested restricted common stock at December 31, 2019 1,428 $ 24.26 Granted 1,677 $ 32.90 Vested (1,107) $ 20.66 Unvested restricted common stock at December 31, 2020 1,998 $ 34.00 Employee Stock Purchase Plan On November 7, 2013, the Company’s 2013 Employee Stock Purchase Plan (ESPP) became effective. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for twelve-month offering periods, and each offering period will include purchase periods, which will be the approximately six-month period commencing with one exercise date and ending with the next exercise date. Employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the exercise date. The number of shares available for sale under the ESPP were and will be increased annually on the first day of each fiscal year, equal to the least of i) 11.3 million shares; ii) 1% of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding fiscal year; or iii) such other amount as determined by the Board of Directors. During the years ended December 31, 2020 and 2019, employees purchased an aggregate of 2.3 million and 1.6 million shares, respectively, under this plan at a weighted average price of $24.65 and $26.62 per share, respectively. Stock Option Activity A summary of stock option activity for the year ended December 31, 2020 is as follows (in thousands, except years and per share data): Options Outstanding Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2019 3,227 $ 9.84 2.65 $ 74,630 Options granted and assumed in connection with acquisitions 128 $ 7.08 Options exercised (1,882) $ 2.89 Options canceled (37) $ 0.91 Outstanding at December 31, 2020 1,436 $ 18.97 3.39 $ 50,534 Exercisable at December 31, 2020 1,415 $ 18.87 3.32 $ 49,932 The aggregate intrinsic value in the table above represents the difference between the fair value of common stock and the exercise price of outstanding, in-the-money stock options. The total intrinsic values of stock options exercised in the years ended December 31, 2020, 2019 and 2018 were $78.5 million, $13.1 million and $16.9 million, respectively. Performance Restricted Stock Units Activity The Company grants restricted stock units to certain of its executive officers periodically that vest based on the Company’s attainment of the annual financial performance goals and the executives’ continued employment through the vesting date (PRSUs). These PRSUs are granted when the annual performance targets are set and the awards are approved by the Compensation Committee of the Board of Directors, generally in the first quarter of each financial year. The Company granted PRSUs with a vesting period of one The following table summarizes the activity related to the Company’s PRSUs for the year ended December 31, 2020 (in thousands, except per share data): PRSUs Outstanding Shares Weighted- Unvested and outstanding at December 31, 2019 646 $ 31.52 Granted (100% target level) 729 $ 27.77 Vested (100% target level) (646) $ 31.52 Unvested and outstanding at December 31, 2020 729 $ 27.77 The PRSUs unvested and outstanding at December 31, 2020 include 729,000 shares of performance-based awards for the 2020 performance period, which are expected to vest at 50% of target, or 365,000 PRSUs over three years, based on the financial results of the 2020 financial year. The total fair value of PRSUs vested during the year ended December 31, 2020 and 2019 was $22.7 million and $23.2 million, respectively. The Company also grants restricted stock units to certain of its executive officers that vest based on Twitter stock price performance relative to a broad-market index over a performance period of two three two The following table summarizes the activity related to the Company’s TSR RSUs for the year ended December 31, 2020 (in thousands, except per share data): TSR RSUs Outstanding Shares Weighted- Unvested and outstanding at December 31, 2019 759 $ 41.15 Granted (100% target level) 487 $ 31.16 Additional earned performance shares related to 2019 grants 52 $ 54.97 Vested (116% target level) (381) $ 54.97 Unvested and outstanding at December 31, 2020 917 $ 30.90 The TSR RSUs unvested and outstanding at December 31, 2020 include 430,000 shares of market-based awards for the 2019 to 2020 performance period, which are expected to vest at 52% of target, or 224,000 TSR RSUs in 2021, based on the financial results of the 2019 and 2020 financial years. The total fair value of TSR RSUs vested during the year ended December 31, 2020 and 2019 was $13.4 million and $3.7 million, respectively. RSU Activity The following table summarizes the activity related to the Company’s RSUs, excluding PRSUs and TSR RSUs, for the year ended December 31, 2020. For purposes of this table, vested RSUs represent the shares for which the service condition had been fulfilled as of each respective date (in thousands, except per share data): RSUs Outstanding Shares Weighted- Unvested and outstanding at December 31, 2019 31,731 $ 29.74 Granted 23,795 $ 32.24 Vested (15,768) $ 27.41 Canceled (3,147) $ 30.78 Unvested and outstanding at December 31, 2020 36,611 $ 32.28 The total fair value of RSUs vested during the years ended December 31, 2020, 2019, and 2018 was $557.1 million, $454.5 million, and $445.7 million, respectively. Stock-Based Compensation Expense Stock-based compensation expense is allocated based on the cost center to which the award holder belongs. Total stock-based compensation expense by function is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Cost of revenue $ 32,020 $ 22,797 $ 17,289 Research and development 281,092 209,063 183,799 Sales and marketing 98,748 85,739 71,305 General and administrative 63,072 60,426 53,835 Total stock-based compensation expense $ 474,932 $ 378,025 $ 326,228 The amount of incremental stock-based compensation recorded in relation to the modification of stock-based awards was not material for the years ended December 31, 2020, 2019 and 2018. The Company capitalized $34.6 million, $37.5 million and $41.4 million of stock-based compensation expense associated with the cost for developing software for internal use in the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, there was $1.14 billion of gross unamortized stock-based compensation expense related to unvested awards which is expected to be recognized over a weighted-average period of 2.7 years. The Company accounts for forfeitures as they occur.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The domestic and foreign components of income (loss) before income taxes for the years ended December 31, 2020, 2019 and 2018 are as follows (in thousands): Year Ended December 31, 2020 2019 2018 Domestic $ (72,850) $ 317,135 $ 193,500 Foreign 21,911 73,004 230,044 Income (loss) before income taxes $ (50,939) $ 390,139 $ 423,544 The components of the provision (benefit) for income taxes for the years ended December 31, 2020, 2019 and 2018 are as follows (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ (199) $ 563 $ (1,661) State 677 3,375 4,083 Foreign 19,813 43,053 17,246 Total current provision for income taxes 20,291 46,991 19,668 Deferred: Federal (35,651) 2,023 (711,084) State (2,248) 2,050 (49,047) Foreign 1,102,295 (1,126,584) (41,589) Total deferred provision (benefit) for income taxes 1,064,396 (1,122,511) (801,720) Provision (benefit) for income taxes $ 1,084,687 $ (1,075,520) $ (782,052) The following is a reconciliation of the income tax at the federal statutory rate to the Company’s provision (benefit) for income taxes for the years ended December 31, 2020, 2019 and 2018 (in thousands): Year Ended December 31, 2020 2019 2018 Income tax at federal statutory rate $ (10,697) 81,929 $ 88,944 State taxes, net of federal benefit (1,246) 4,286 (35,521) Stock-based compensation (27,127) (19,005) (27,228) Research and development credits (40,707) (33,044) (23,490) Valuation allowance 1,104,732 (724) (758,707) Nondeductible other expenses 7,438 12,266 682 Nondeductible Federal Trade Commission settlement accrual 31,500 — — Deferred tax asset on intra-entity transfer of intangible assets — (1,203,381) — Foreign rate differential 22,078 79,186 (27,002) Other (1,284) 2,967 270 Provision (benefit) for income taxes $ 1,084,687 $ (1,075,520) $ (782,052) The tax effects of temporary differences and related deferred tax assets and liabilities as of December 31, 2020 and 2019 are as follows (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 421,411 $ 390,005 Tax credits 485,106 425,011 Fixed assets and intangible assets 1,280,597 1,214,070 Operating lease liability 230,837 170,817 Other 82,596 90,115 Total deferred tax assets 2,500,547 2,290,018 Valuation allowance (1,457,137) (223,775) Total deferred tax assets, net of valuation allowance 1,043,410 2,066,243 Deferred tax liabilities: Operating lease right-of-use asset (215,663) (157,845) Other (32,451) (1,138) Total deferred tax liabilities (248,114) (158,983) Net deferred tax assets $ 795,296 $ 1,907,260 During the year ended December 31, 2020, the Company reassessed the ability to realize deferred tax assets by considering the available positive and negative evidence. As of June 30, 2020, the Company concluded that the deferred tax assets in a foreign subsidiary were not more-likely-than-not to be realized and recorded a full valuation allowance against such deferred tax assets in the approximate amount of $1.10 billion. In evaluating the need for a valuation allowance, the Company considered its recent operating results which resulted in a cumulative taxable loss in the foreign subsidiary for the twelve quarters ended June 30, 2020. The twelve quarters cumulative taxable losses from operations is considered a significant piece of negative evidence and outweighs other positive evidence, such as projections of future income. The twelve quarters cumulative taxable losses and projected near-term losses in the foreign subsidiary were largely driven by the negative impact from the COVID-19 pandemic as it caused decreased advertiser demand in the first half of 2020. If there are favorable changes to actual operating results or to projections of future income, the Company may determine that it is more-likely-than-not such deferred tax assets may be realizable. As of December 31, 2020, there have been no changes to the Company's conclusion. As of December 31, 2020, the Company had $796.3 million of deferred tax assets for which it has not established a valuation allowance, related to the U.S. federal, states other than Massachusetts and California, and certain international subsidiaries. The Company completed its reassessment of the ability to realize these assets and concluded that a valuation allowance was not required. During the year ended December 31, 2019, the Company transferred certain intangible assets among its wholly-owned subsidiaries to align its structure to its evolving operations, which resulted in the establishment of deferred tax assets and the recognition of a deferred tax benefit from income tax of $1.21 billion. During the year ended December 31, 2018, the Company released the valuation allowance related to most of the United States federal and all states deferred tax assets with the exception of California and Massachusetts, as well as Brazil, which resulted in an income tax benefit of $845.1 million. The Company continues to maintain a valuation allowance related to specific net deferred tax assets where it is not more likely than not that the deferred tax assets will be realized, which include all capital losses and California and Massachusetts net deferred tax assets. The Company concluded, based upon the preponderance of positive evidence (i.e. cumulative profit before tax adjusted for permanent items over the previous twelve quarters, a history of taxable income in recent periods, and the current forecast of income before taxes for the United States going forward) over negative evidence and the anticipated ability to use the deferred tax assets, that it was more likely than not that the deferred tax assets could be realized. If there are unfavorable changes to actual operating results or to projections of future income, the Company may determine that it is more likely than not such deferred tax assets may not be realizable. The Company has recorded a valuation allowance of $1.21 billion against its gross deferred tax asset balance in a foreign subsidiary as of December 31, 2020, a valuation allowance of $15.2 million and $13.9 million against its gross U.S. federal deferred tax asset balance as of December 31, 2020, and 2019, respectively, as well as a valuation allowance of $229.2 million and $209.9 million against its gross state deferred tax asset balance as of December 31, 2020 and 2019, respectively. At December 31, 2020, the Company had $2.19 billion of U.S. federal, $1.28 billion of U.S. state, and $59.2 million of Brazil net operating losses, which will begin to expire in 2034 for federal and 2024 for state tax purposes, if not utilized. The Brazil net operating losses have no expiration date. The Company also has $398.4 million and $297.1 million of U.S. federal and state research credit carryforwards, respectively. The U.S. federal credit carryforward will begin to expire in 2027, if not utilized. The majority of state research tax credits have no expiration date. A small portion of state research tax credits will begin to expire in 2030, if not utilized. Additionally, the Company has California Enterprise Zone Credit carryforwards of $19.1 million which will begin to expire in 2023, if not utilized. Utilization of the net operating loss and credit carryforwards may be subject to an annual limitation due to the ownership change limitations provided by the Internal Revenue Code of 1986, as amended (the Code), and similar state provisions. Any annual limitation may result in the expiration of net operating losses and credits before utilization. As of December 31, 2020, the Company had $354.6 million of unrecognized tax benefits, of which $275.6 million could result in a reduction of the Company’s effective tax rate, if recognized. The remainder of the unrecognized tax benefits would not affect the effective tax rate due to the full valuation allowance recorded for California and Massachusetts deferred tax assets. On June 7, 2019, the Ninth Circuit Court of Appeals issued a new opinion in the case of Altera Corp. v. Commissioner (Altera), which upheld Department of Treasury regulations requiring related parties in an intercompany cost-sharing arrangement to share expenses related to stock-based compensation. In February 2020, Altera Corp. filed a petition to appeal the decision with the Supreme Court of the United States. On June 22, 2020, the Supreme Court denied the petition. The Company filed its 2019 U.S. Federal and state tax returns in the fourth quarter of 2020 and included certain adjustments related to Altera for which the Company previously recognized a reserve. As a result, the Company's unrecognized tax benefits decreased by $96.9 million in the fourth quarter of 2020 with no impact on its effective tax rate. A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Gross unrecognized tax benefits at the beginning of the year $ 419,858 $ 332,314 $ 259,781 Increases related to prior year tax positions 5,943 54,743 20,000 Decreases related to prior year tax positions (99,540) (2,537) (13,174) Increases related to current year tax positions 28,337 35,338 66,249 Statute of limitations expirations — — (542) Gross unrecognized tax benefits at the end of the year $ 354,598 $ 419,858 $ 332,314 Total unrecognized tax benefits are recorded on the Company’s consolidated balance sheets as follows (in thousands): December 31, 2020 2019 Total unrecognized tax benefits balance $ 354,598 $ 419,858 Amounts netted against related deferred tax assets (331,339) (401,818) Unrecognized tax benefits recorded on consolidated balance sheets $ 23,259 $ 18,040 The Company recognizes interest and/or penalties related to income tax matters as a component of income tax expense. During the years ended December 31, 2020, 2019, and 2018, the Company recognized immaterial amounts of interest and penalties in income tax expense. As of December 31, 2020 and 2019, the Company had $7.2 million and $5.3 million of interest and penalties included in uncertain tax positions, respectively. The Company is subject to taxation in the United States and various foreign jurisdictions. Earnings from non-U.S. activities are subject to local country income tax. The material jurisdictions where the Company is subject to potential examination by tax authorities include the United States, California and Ireland. The Company believes that it has reserved adequate amounts for these jurisdictions. The Company’s 2007 to 2019 tax attributes remain subject to potential examination by the United States and California, and its 2016 to 2019 tax years remain subject to potential examination in Ireland. The Company remains subject to potential examination in various other jurisdictions that are not expected to result in material tax adjustments. The Company does not believe that its unrecognized tax benefits will materially change within the next 12 months.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Credit Facility The Company has a revolving credit agreement with certain lenders, which provides for a $500.0 million unsecured revolving credit facility maturing on August 7, 2023. The Company is obligated to pay interest on loans under the credit facility and other customary fees for a credit facility of this size and type, including an upfront fee and an unused commitment fee. The interest rate for the credit facility is determined based on calculations using certain market rates as set forth in the credit agreement. In addition, the credit facility contains restrictions on payments including cash payments of dividends. As of December 31, 2020, no amounts had been drawn under the credit facility. Contractual Obligations The Company's principal commitments consist of obligations under the Notes (including principal and coupon interest), operating and finance leases for equipment, office space and co-located data center facilities, as well as non-cancellable contractual commitments. The following table summarizes its commitments to settle contractual obligations in cash as of December 31, 2020: Payments Due by Year Total 2021 2022-2023 2024-2025 Thereafter (In thousands) 2021 Notes $ 963,540 $ 963,540 $ — $ — $ — 2024 Notes 1,160,039 2,867 5,734 1,151,438 — 2025 Notes 1,016,825 3,740 7,480 1,005,605 — 2027 Notes 889,819 27,106 54,213 54,287 754,213 Operating lease obligations (1) 1,671,283 218,869 430,418 354,254 667,742 Finance lease obligations 569 569 — — — Other contractual commitments (2) 1,669,012 227,601 519,866 734,827 186,718 Total contractual obligations $ 7,371,087 $ 1,444,292 $ 1,017,711 $ 3,300,411 $ 1,608,673 (1) The Company has entered into several sublease agreements for office space that it is not fully utilizing. Under the sublease agreements, the Company will receive approximately $10.3 million in sublease income over the next two years. (2) Other contractual commitments are non-cancelable contractual commitments primarily related to the Company’s infrastructure services and other services arrangements. Legal Proceedings Beginning in September 2016, multiple putative class actions and derivative actions were filed in state and federal courts in the United States against the Company and the Company’s directors and/or certain former officers alleging that false and misleading statements, made in 2015, are in violation of securities laws and breached fiduciary duty. The putative class actions were consolidated in the U.S. District Court for the Northern District of California. On October 16, 2017, the court granted in part and denied in part the Company’s motion to dismiss. On July 17, 2018, the court granted plaintiffs' motion for class certification in the consolidated securities action. In January 2021, the Company entered into a binding agreement to settle the pending shareholder derivative lawsuits. The proposed settlement resolves all claims asserted against the Company and the other named defendants in the derivative lawsuits without any liability or wrongdoing attributed to them personally or the Company. Under the terms of the proposed settlement, the Company's board of directors will adopt and implement certain corporate governance modifications. In addition, the Company will receive $38.0 million of insurance proceeds to be used for general corporate purposes. The settlement will not require the Company to make any payment, aside from covering certain administrative costs related to the settlement. The settlement agreement is subject to final approval by the Court of Chancery of the State of Delaware, which is scheduled for March 2021. The shareholder class action remains pending and is scheduled for trial on September 20, 2021. Beginning in October 2019, putative class actions were filed in the U.S. District Court for the Northern District of California against the Company and certain of the Company’s officers alleging violations of securities laws in connection with the Company’s announcements that it had discovered and taken steps to remediate issues related to certain user settings designed to target advertising that were not working as expected and seeking unspecified damages. The Company disputes the claims and intends to defend the lawsuit vigorously. In December 2020, the district court dismissed the plaintiffs’ claims. The case is currently on appeal to the United States Court of Appeal for the Ninth Circuit. From time to time the Company notifies the Irish Data Protection Commission, its designated European privacy regulator under the European Union General Data Protection Regulation, or GDPR, and other regulators, of certain personal data breaches and privacy issues, and is subject to inquiries and investigations regarding various aspects of our regulatory compliance. The Company is currently the subject of inquiries by the Irish Data Protection Commission with respect to its compliance with the GDPR. On July 28, 2020, the Company received a draft complaint from the Federal Trade Commission (FTC) alleging violations of the Company’s 2011 consent order with the FTC and the Federal Trade Commission Act. The allegations relate to the Company’s use of phone number and/or email address data provided for safety and security purposes for targeted advertising during periods between 2013 and 2019. The Company estimates that the range of probable loss in this matter is $150.0 million to $250.0 million and recorded an accrual of $150.0 million in the three months ended June 30, 2020. The accrual is included in accrued and other current liabilities in the consolidated balance sheet and in general and administrative expenses in the consolidated statements of operations. The matter remains unresolved, and there can be no assurance as to the timing or the terms of any final outcome. On January 15, 2021, a derivative action was filed in the Delaware Chancery Court against certain directors of the Company alleging that the directors violated their fiduciary duties in deciding to enter into the Cooperation Agreement with certain affiliates of Elliott Management Corporation, to enter into the Investment Agreement with an affiliate of Silver Lake Partners, and to authorize a program to repurchase up to $2.0 billion of the Company's common stock. The Company and the directors dispute the claims and intend to defend the lawsuit vigorously. The Company is also currently involved in, and may in the future be involved in, legal proceedings, claims, investigations, and government inquiries and investigations arising in the ordinary course of business. These proceedings, which include both individual and class action litigation and administrative proceedings, have included, but are not limited to matters involving content on the platform, intellectual property, privacy, data protection, consumer protection, securities, employment, and contractual rights. Legal fees and other costs associated with such actions are expensed as incurred. The Company assesses, in conjunction with its legal counsel, the need to record a liability for litigation and contingencies. With respect to the cases, actions, and inquiries described above, the Company evaluates the associated developments on a regular basis and accrues a liability when it believes a loss is probable and the amount can be reasonably estimated. I n addition, the Company believes there is a reasonable possibility that it may incur a loss in some of these matters and the loss may be material or exceed its estimated ranges of possible loss. With respect to the matters described above that do not include an estimate of the amount of loss or range of possible loss, such losses or range of possible losses either are not material or may be material but cannot be estimated. The outcomes of the matters described in this section, such as whether the likelihood of loss is remote, reasonably possible, or probable, or if and when the reasonably possible range of loss is estimable, are inherently uncertain. If one or more of these matters were resolved against the Company for amounts above management’s estimates, the Company’s financial condition and results of operations, including in a particular reporting period in which any such outcome becomes probable and estimable, could be materially adversely affected. Non-Income Taxes The Company is under various non-income tax audits by domestic and foreign tax authorities. These audits primarily revolve around routine inquiries, refund requests, and employee benefits. The Company accrues non-income taxes that may result from these audits when they are probable and can be reasonably estimated. Due to the complexity and uncertainty of some of these matters, however, as well as the judicial process in certain jurisdictions, the final outcome of these audits may be materially different from the Company's expectations. Indemnification In the ordinary course of business, the Company often includes standard indemnification provisions in its arrangements with its customers, partners, suppliers and vendors. Pursuant to these provisions, the Company may be obligated to indemnify such parties for losses or claims suffered or incurred in connection with its service, breach of representations or covenants, intellectual property infringement or other claims made against such parties. These provisions may limit the time within which an indemnification claim can be made. It is not possible to determine the maximum potential amount under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. The Company has never incurred significant expense defending its licensees against third-party claims, nor has it ever incurred significant expense under its standard service warranties or arrangements with its customers, partners, suppliers and vendors. Accordingly, the Company had no liabilities recorded for these provisions as of December 31, 2020 and 2019.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsCertain of the Company’s directors have affiliations with customers of the Company. The Company recognized revenue under contractual obligations from such customers of $22.0 million for each of the years ended December 31, 2020 and 2019 and $25.9 million for the year December 31, 2018. The Company had outstanding receivable balances of $5.0 million and $4.2 million from such customers as of December 31, 2020 and 2019, respectively.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanThe Company has a 401(k) Plan that qualifies as a deferred compensation arrangement under Section 401 of the Internal Revenue Code. Under the 401(k) Plan, participating employees may defer a portion of their pretax earnings not to exceed the maximum amount allowable. Matching contributions are based upon the amount of the employees’ contributions subject to certain limitations. The matching contributions made by the Company were $11.0 million, $8.8 million, and $6.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Segment Information and Operati

Segment Information and Operations by Geographic Area	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information and Operations by Geographic Area	Segment Information and Operations by Geographic Area The Company has a single operating segment and reporting unit structure. The Company’s chief operating decision-maker is the Chief Executive Officer who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. Revenue See Note 3 – Revenue for further details. Property and Equipment, net See Note 6 – Property and Equipment, Net for further details.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS FOR THE YEARS ENDED DECEMBER 31, 2020, 2019 AND 2018 Balance at Charged to Charged/ Balance at (In thousands) Allowance for Deferred Tax Assets: Year ended December 31, 2020 $ 223,775 $ 1,124,132 $ 109,230 $ 1,457,137 Year ended December 31, 2019 $ 210,862 $ 12,913 $ — $ 223,775 Year ended December 31, 2018 $ 1,021,326 $ (817,529) $ 7,065 $ 210,862 Balance at Additions Write-off/ Balance at (In thousands) Allowance for Doubtful Accounts: Year ended December 31, 2020 $ 2,401 $ 17,190 $ (2,645) $ 16,946 Year ended December 31, 2019 $ 3,559 $ 3,083 $ (4,241) $ 2,401 Year ended December 31, 2018 $ 5,430 $ 1,610 $ (3,481) $ 3,559

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Prior Period Reclassifications	Prior Period Reclassifications Certain prior period amounts have been reclassified to conform to the current period presentation.
Use of Estimates	Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with generally accepted accounting principles in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, as well as related disclosure of contingent assets and liabilities. Actual results could differ materially from the Company’s estimates. To the extent that there are material differences between these estimates and actual results, the Company’s financial condition or operating results will be affected. The Company bases its estimates on past experience and other assumptions that the Company believes are reasonable under the circumstances, and the Company evaluates these estimates on an ongoing basis. COVID-19 Impacts The COVID-19 pandemic has caused, and continues to cause, widespread economic disruption and has impacted the Company in a number of ways, most notably a significant decrease in global advertising spend in the first half of 2020, followed by a recovery in the second half of 2020. The Company expects the extent of the impact on its financial and operational results will depend on the duration and severity of the economic disruption caused by the COVID-19 pandemic. As of December 31, 2020, the Company had $7.47 billion of cash, cash equivalents and short-term investments in marketable securities. If required, the Company may take certain liquidity mitigation actions in the future; however, it does not believe such actions are necessary based on its current forecasts. The Company believes that the existing cash, cash equivalents and short-term investments balances, together with cash generated by operations will be sufficient to meet its working capital and capital expenditure requirements in the foreseeable future based on its current expectations of the impact of the COVID-19 pandemic. The Company considered the impacts of the COVID-19 pandemic on its significant estimates and judgments used in applying its accounting policies in 2020. In light of the pandemic, there is a greater degree of uncertainty in applying these judgments and depending on the duration and severity of the pandemic, changes to its estimates and judgments could result in a meaningful impact to its financial statements in future periods. Some of the more reasonably possible and significant items subject to a greater degree of uncertainty during this time include estimates of the valuation allowance against deferred tax assets, the carrying value of investments in privately-held companies, and credit losses related to accounts receivable, unbilled revenue, and investments in debt securities.
Revenue Recognition	Revenue Recognition The Company generates the substantial majority of its revenue from the sale of advertising services with the remaining balance from data licensing and other arrangements. The Company generates its advertising revenue primarily from the sale of its Promoted Products: (i) Promoted Tweets, (ii) Promoted Accounts and (iii) Promoted Trends. Promoted Tweets and Promoted Accounts are pay-for-performance advertising products or pay on impressions delivered, each priced through an auction. Promoted Trends are featured by geography and offered on a fixed-fee-per-day basis. Advertisers are obligated to pay when a person engages with a Promoted Tweet, follows a Promoted Account, when an impression is delivered, or when a Promoted Trend is displayed for an entire day in a particular country or on a global basis. These advertising services may be sold in combination as a bundled arrangement or separately on a stand-alone basis. For the Company's Promoted Product arrangements, significant judgments are (i) identifying the performance obligations in the contract, (ii) determining the basis for allocating contract consideration to performance obligations, (iii) determining whether the Company is the principal or the agent in arrangements where another party is involved in providing specified services to a customer, and (iv) estimating the transaction price to be allocated for contracts with tiered rebate provisions. The Company may generate revenue from the sale of certain Promoted Tweets through placement by Twitter of advertiser ads against third-party publisher content. The Company will pay the third-party publisher a revenue share fee for its right to monetize their content. In such transactions, advertisers are contracting to obtain a single integrated advertising service, the Promoted Tweet combined with the third-party publisher content, and the Company obtains control of the third-party publisher content displayed on Twitter that it then combines with the advertiser ads within the Promoted Tweet. Therefore, the Company reports advertising revenue generated from these transactions on a gross basis and records the related third-party content monetization fees as cost of revenue. The Company also generates advertising revenue by selling services in which the Company places ads on third-party publishers’ websites, applications or other offerings. To fulfill these transactions, the Company purchases advertising inventory from third-party publishers’ websites and applications where the Company has identified the advertisers’ targeted audience and therefore incurs traffic acquisition costs prior to transferring the advertising service to its customers. At such point, the Company has the sole ability to monetize the third-party publishers advertising inventory. In such transactions, the Company obtains control of a right to a service to be performed by the third-party publishers, which gives the Company the ability to direct those publishers to provide the services to the Company's customers on the Company's behalf. Therefore, the Company reports advertising revenue generated from these transactions on a gross basis and records the related traffic acquisition costs as cost of revenue. Fees for the advertising services above are recognized in the period when advertising is delivered as evidenced by a person engaging with a Promoted Tweet or an ad on a third-party publisher website or application in a manner satisfying the types of engagement selected by the advertisers, such as Tweet engagements (e.g., Retweets, replies and likes), website clicks, mobile application installs or engagements, obtaining new followers, or video views, following a Promoted Account, delivery of impressions, or through the display of a Promoted Trend on the Company's platform. The Company has concluded that its data licensing arrangements, which grant customers a right to its intellectual property (IP) for a defined period of time, may contain a single performance obligation satisfied at a point in time (Historical IP) or over time (Future IP), or may contain two or more performance obligations satisfied separately at a point in time (Historical IP) and over time (Future IP). In some of the Company's data licensing arrangements, pricing is a fixed monthly fee over a specified term. In arrangements with a single performance obligation satisfied over time, data licensing revenue is recognized on a straight-line basis over the period in which the Company provides data as the customer consumes and benefits from the continuous data available on an ongoing basis. In arrangements with at least two performance obligations, the Company allocates revenue on a relative basis between the performance obligations based on standalone selling price (SSP) and recognizes revenue as the performance obligations are satisfied. In other data licensing arrangements, the Company charges customers based on the amount of sales they generate from downstream customers using Twitter data. Certain of those royalty-based data licensing arrangements are subject to minimum guarantees. For such arrangements with a minimum guarantee and a single Future IP performance obligation, the Company recognizes revenue for minimum guarantees on a straight-line basis over the period in which the Company provides data. For such arrangements with a minimum guarantee and two or more performance obligations, the Company allocates revenue on a relative basis between the performance obligations based on SSP and recognizes revenue as the performance obligations are satisfied. Royalties in excess of minimum guarantees, if any, are recognized as revenue over the contract term, on a straight-line, cumulative catch-up basis. This reflects the nature of the Company’s performance obligation, which is a series of distinct monthly periods of providing a license of IP. For data licensing arrangements involving two or more performance obligations, the Company uses directly observable standalone transactions to determine SSP of Historical IP. The Company uses standalone transactions and considers all other reasonably available observable evidence to estimate SSP of Future IP. Other revenue is primarily generated from service fees from transactions completed on the Company's mobile ad exchange. The Company's mobile ad exchange enables buyers and sellers to purchase and sell advertising inventory by matching them in the exchange. The Company has determined it is not the principal in the purchase and sale of advertising inventory in transactions between third-party buyers and sellers on the exchange because the Company does not obtain control of the advertising inventory. The Company reports revenue related to its ad exchange services on a net basis for the fees paid by buyers, net of costs related to acquiring the advertising inventory paid to sellers.
Cost of Revenue	Cost of Revenue Cost of revenue includes infrastructure costs, other direct costs including revenue share expenses, amortization expense of technology acquired through acquisitions and amortization of capitalized labor costs for internally developed software, allocated facilities costs, as well as traffic acquisition costs (TAC). Infrastructure costs consist primarily of data center costs related to the Company’s co-located facilities, which include lease and hosting costs, related support and maintenance costs and energy and bandwidth costs, public cloud hosting costs, as well as depreciation of servers and networking equipment, and personnel-related costs, including salaries, benefits and stock-based compensation, for its operations teams. Revenue share expenses are primarily related to payments to providers from whom the Company licenses content, in order to increase engagement on the platform. The fees paid to these content providers may be based on revenues generated, or a minimum guaranteed fee. TAC consists of costs incurred with third parties in connection with the sale to advertisers of advertising products that the Company places on third-party publishers’ websites, applications or other offerings collectively resulting from acquisitions.
Stock-Based Compensation Expense	Stock-Based Compensation Expense The Company accounts for stock-based compensation expense under the fair value recognition and measurement provisions of GAAP. Stock-based awards granted to employees are measured based on the grant-date fair value. For service-based restricted stock awards and performance-based restricted stock awards, the Company recognizes the compensation expense only for those awards expected to meet the performance and service vesting conditions. For service-based restricted stock awards, expense is recognized on a straight-line basis over the requisite service period. The service condition for restricted stock awards is generally satisfied over four years, but has been up to five years in certain circumstances. For performance-based restricted stock awards, expense is recognized on a graded basis over the requisite service period. For market-based restricted stock awards, the Company recognizes the compensation expense on a graded basis over the requisite service period regardless of whether the market condition is satisfied, provided that the requisite service has been provided. The requisite service period for performance-based and market-based restricted stock awards is generally up to three years. The Company accounts for forfeitures as they occur. The Company estimates the fair value of stock options granted and stock purchase rights provided under the Company’s employee stock purchase plan using the Black-Scholes option pricing model on the dates of grant. The compensation expense related to stock options and employee stock purchase rights is recognized on a straight-line basis over the requisite service period. The fair value of market-based restricted stock awards is determined using a Monte Carlo simulation to estimate the grant date fair value. The Company issues restricted stock subject to a lapsing right of repurchase to continuing employees of certain acquired companies. Since these issuances are subject to post-acquisition employment, the Company accounts for them as post-acquisition stock-based compensation expense. The grant-date fair value of restricted stock granted in connection with acquisitions is recognized as stock-based compensation expense on a straight-line basis over the requisite service period.
Acquisitions	Business Combinations The Company allocates the purchase price of the acquisition to the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values at the acquisition dates. The excess of the purchase price over those fair values is recorded as goodwill. During the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations.
Investments in Privately-Held Companies	Investments in Privately-Held Companies The Company makes strategic investments in privately-held companies. The Company also evaluates each investee to determine if the investee is a variable interest entity and, if so, whether the Company is the primary beneficiary of the variable interest entity. The Company has determined, as of December 31, 2020, there were no variable interest entities required to be consolidated in the Company’s consolidated financial statements. The Company’s investments in privately-held companies are primarily non-marketable equity securities without readily determinable fair values. The Company accounts for its investments in privately-held companies either under equity method accounting or by adjusting the carrying value of its non-marketable equity securities to fair value upon observable transactions for identical or similar investments of the same issuer or upon impairment (referred to as the measurement alternative). The investments in privately-held companies are included within Other Assets on the consolidated balance sheets. All gains and losses on non-marketable equity securities, realized and unrealized, are recognized in other income (expense), net in the consolidated statements of operations. The Company periodically evaluates the carrying value of the investments in privately-held companies when events and circumstances indicate that the carrying amount of the investment may not be recovered. The Company estimates the fair value of the investments to assess whether impairment losses shall be recorded using Level 3 inputs. These investments include the Company’s holdings in privately-held companies that are not exchange traded and therefore not supported with observable market prices; hence, the Company may determine the fair value by reviewing equity valuation reports, current financial results, long-term plans of the privately-held companies, the amount of cash that the privately-held companies have on-hand, the ability to obtain additional financing and overall market conditions in which the privately-held companies operate or based on the price observed from the most recent completed financing.
Loss Contingencies	Loss Contingencies The Company is currently involved in, and may in the future be involved in, legal proceedings, claims, investigations, and government inquiries and investigations arising in the ordinary course of business. The Company records a liability when it believes that it is both probable that a loss has been incurred and the amount or range can be reasonably estimated. If the Company determines there is a reasonable possibility that it may incur a loss and the loss or range of loss can be estimated, it discloses the possible loss to the extent material. Significant judgment is required to determine both probability and the estimated amount. The Company reviews these provisions on a quarterly basis and adjusts these provisions accordingly to reflect the impact of negotiations, settlements, rulings, advice of legal counsel, and updated information.
Operating and Finance Leases	Operating and Finance Leases The Company has operating leases primarily for office space and data center facilities. The determination of whether an arrangement is a lease or contains a lease is made at inception by evaluating whether the arrangement conveys the right to use an identified asset and whether the Company obtains substantially all of the economic benefits from and has the ability to direct the use of the asset. Operating leases are included in operating lease right-of-use assets, operating lease liabilities, short-term, and operating lease liabilities, long-term on the Company’s consolidated balance sheets. With the exception of initial adoption of the new lease standard, where the Company’s incremental borrowing rate used was the rate on the adoption date (January 1, 2019), operating lease ROU assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at the lease commencement date. To determine the incremental borrowing rate used to calculate the present value of future lease payments, the Company uses information including the Company’s credit rating, interest rates of similar debt instruments of entities with comparable credit ratings, the Company's recent debt issuances, and Twitter, Inc.’s guarantee of certain leases in foreign jurisdictions, as applicable. Certain lease agreements contain options for the Company to renew or early terminate a lease. The Company considers these options, which may be elected at the Company’s sole discretion, in determining the lease term on a lease-by-lease basis. Leases with an initial term of twelve months or less are not recognized on the consolidated balance sheets. The Company recognizes lease expense for these leases on a straight-line basis over the term of the lease. The Company also has server and networking equipment lease arrangements with original lease terms ranging from three four The Company’s lease agreements generally do not contain any material residual value guarantees or material restrictive covenants. Certain of the Company’s leases contain free or escalating rent payment terms. Additionally, certain lease agreements contain lease components (for example, fixed payments such as rent) and non-lease components such as common-area maintenance costs. For each asset class of the Company’s leases—real estate offices, data centers, and equipment—the Company has elected to account for both of these provisions as a single lease component. For arrangements accounted for as a single lease component, there may be variability in future lease payments as the amount of the non-lease components is typically revised from one period to the next. These variable lease payments, which are primarily comprised of common-area maintenance, utilities, and real estate taxes that are passed on from the lessor in proportion to the space leased by the Company, are recognized in operating expenses in the period in which the obligation for those payments was incurred. The Company recognizes lease expense for its operating leases in operating expenses on a straight-line basis over the term of the lease. The Company subleases certain leased office space to third parties when it determines there is excess leased capacity. Certain of these subleases contain both lease and non-lease components. The Company has elected to account for both of these provisions as a single lease component. Sublease rent income is recognized as an offset to operating expense on a straight-line basis over the lease term. In addition to sublease rent, variable non-lease costs such as common-area maintenance, utilities, and real estate taxes are charged to subtenants over the duration of the lease for their proportionate share of these costs. These variable non-lease income receipts are recognized in operating expenses as a reduction to costs incurred by the Company in relation to the head lease.
Cash, Cash Equivalents and Investments	Cash, Cash Equivalents and Investments The Company invests its excess cash primarily in short-term fixed income securities, including government and investment-grade debt securities and money market funds. The Company classifies all liquid investments with stated maturities of three months or less from date of purchase as cash equivalents. The Company classifies all marketable securities for use in current operations, even if the security matures beyond 12 months, and presents them as short-term investments in the consolidated balance sheets. As of December 31, 2020 and 2019, the Company has restricted cash balances of $2.3 million and $1.9 million, respectively, within prepaid expenses and other current assets and $20.6 million and $26.7 million, respectively, in other assets on the accompanying consolidated balance sheets based upon the term of the remaining restrictions. These restricted cash balances are primarily cash deposits to back letters of credit related to certain property leases. The Company determines the appropriate classification of its investments in marketable securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company has classified and accounted for its marketable securities as available-for-sale. After considering the Company’s capital preservation objectives, as well as its liquidity requirements, the Company may sell securities prior to their stated maturities. The Company carries its available-for-sale securities at fair value. The Company reports the unrealized gains and losses, net of taxes, as a component of stockholders’ equity, except for unrealized losses determined to be credit-related, which are recorded as other income (expense), net in the consolidated statements of operations and reports an allowance for credit losses in short-term investments on the balance sheet, if any. The Company determines any realized gains or losses on the sale of marketable securities on a specific identification method and records such gains and losses as a component of other income (expense), net. Interest earned on cash, cash equivalents, and marketable securities was $88.2 million, $157.7 million, and $111.2 million during the years ended December 31, 2020, 2019 and 2018, respectively. These amounts are recorded in interest income in the accompanying consolidated statements of operations.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, short-term investments and accounts receivable. The primary focus of the Company’s investment strategy is to preserve capital and meet liquidity requirements. The Company’s investment policy addresses the level of credit exposure by limiting the concentration in any one corporate issuer or sector and establishing a minimum allowable credit rating. To manage the risk exposure, the Company invests cash equivalents and short-term investments in a variety of fixed income securities, including government and investment-grade debt securities and money market funds. The Company places its cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits, if any. The Company’s accounts receivable are typically unsecured and are derived from customers around the world in different industries. The Company includes terms in its contracts providing the ability to stop transferring promised goods or services, performs ongoing credit evaluations of its customers, and maintains allowances for potential credit losses. Historically, such losses have been within management’s expectations. As of December 31, 2020 and 2019, no single customer accounted for more than 10% of the Company’s net accounts receivable balances. No single customer accounted for more than 10% of the Company’s revenue in the years ended December 31, 2020, 2019 and 2018. The Company’s note hedge transactions, entered into in connection with the Convertible Notes, as defined and further described in Note 5 – Fair Value Measurements, and its derivative financial instruments expose the Company to credit risk to the extent that its counterparties may be unable to meet the terms of the transactions. The Company mitigates this risk by limiting its counterparties to major financial institutions and using multiple financial institutions as counterparties in its hedge transactions.
Accounts Receivable, Net	Accounts Receivable, NetThe Company records accounts receivable at the invoiced amount. The Company maintains an allowance for doubtful accounts to reserve for potentially uncollectible receivable amounts. In evaluating the Company’s ability to collect outstanding receivable balances, the Company considers various factors including the age of the balance, the creditworthiness of the customer, which is assessed based on ongoing credit evaluations and payment history, the customer’s current financial condition, and considers macroeconomic factors to estimate expected future credit losses. In the year ended December 31, 2020, the Company recorded a $17.2 million increment in the allowance for doubtful accounts, offset by $2.7 million of write-offs and other adjustments.
Unbilled Revenue (Contract Assets)	Unbilled Revenue (Contract Assets) The Company evaluates whether its unbilled revenue is exposed to potential credit losses by considering factors such as the creditworthiness of its customers, the term over which unbilled revenue will be recognized, historical impairment of unbilled revenue, and contemplation of projected macroeconomic factors. As of December 31, 2020, the Company recorded an immaterial amount of allowance for credit losses on unbilled revenue.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life. The estimated useful lives of property and equipment are described below: Property and Equipment Estimated Useful Life Computer hardware, networking and office equipment Three Computer software Up to five Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term The Company reviews the remaining estimated useful lives of its property and equipment on an ongoing basis. Management is required to use judgment in determining the estimated useful lives of such assets. Changes in circumstances such as technological advances, changes to the Company’s business model, changes in the Company’s business strategy, or changes in the planned use of property and equipment could result in the actual useful lives differing from the Company’s current estimates. In cases where the Company determines that the estimated useful life of property and equipment should be shortened or extended, the Company would apply the new estimated useful life prospectively. The Company reviews property and equipment for impairment when events or circumstances indicate the carrying amount may not be recoverable. Costs of maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. Upon retirement or sale, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is reflected in operating expenses.
Capitalization of Interest	Capitalization of InterestInterest costs are capitalized for assets that are constructed for the Company’s own internal use, including internally developed software and property and equipment, for the period of time to get them ready for their intended use.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired in a business combination. Goodwill is not amortized, but is tested for impairment at least annually or more frequently if events or changes in circumstances indicate that the asset may be impaired. The Company’s impairment tests are based on a single operating segment and reporting unit structure. If the carrying value of the reporting unit exceeds its fair value, an impairment charge is recognized for the excess of the carrying value of the reporting unit over its fair value.
Intangible Assets	Intangible AssetsIntangible assets are carried at cost and amortized on a straight-line basis over their estimated useful lives of up to eleven years. The Company reviews identifiable amortizable intangible assets to be held and used for impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated undiscounted cash flows resulting from use of the asset and its eventual disposition. Measurement of any impairment loss is based on the excess of the carrying value of the asset over its fair value.
Fair Value Measurements	Fair Value Measurements The Company classifies and discloses assets and liabilities measured at fair value on a recurring basis, as well as fair value measurements of assets and liabilities measured on a nonrecurring basis in periods subsequent to initial measurement, in a three-tier fair value hierarchy as described below. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs that may be used to measure fair value are as follows: Level 1—Observable inputs, such as quoted prices in active markets for identical assets or liabilities. Level 2—Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active 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—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
Internal Use Software and Website Development Costs	Internal Use Software and Website Development Costs The Company capitalizes certain costs incurred in developing software programs or websites for internal use. The Company capitalizes these costs once the preliminary project stage is complete, and it is probable that the project will be completed and the software will be used to perform the function intended. In the years ended December 31, 2020, 2019 and 2018, the Company capitalized costs totaling approximately $109.3 million, $127.5 million and $121.0 million, respectively. Capitalized internal use software development costs are included in property and equipment, net. Included in the capitalized amounts above are $34.6 million, $37.5 million and $41.4 million of stock-based compensation expense in the years ended December 31, 2020, 2019 and 2018, respectively.
Income Taxes	Income Taxes The Company is subject to income taxes in the United States and several foreign jurisdictions. Significant judgment is required in determining its provision (benefit) for income taxes and income tax assets and liabilities, including evaluating uncertainties in the application of accounting principles and complex tax laws. The Company records a provision (benefit) for income taxes for the anticipated tax consequences of the reported results of operations using the asset and liability method. Under this method, the Company recognizes deferred income tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities, as well as for loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. The Company recognizes the deferred income tax effects of a change in tax rates in the period of the enactment. The Company records a valuation allowance to reduce its deferred tax assets to the net amount that it believes is more likely than not to be realized. The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. Although the Company believes it has adequately reserved for its uncertain tax positions (including net interest and penalties), it can provide no assurance that the final tax outcome of these matters will not be different. The Company makes adjustments to these reserves in accordance with income tax accounting guidance when facts and circumstances change, such as the closing of a tax audit. To the extent that the final tax outcome of these matters is different from the amounts recorded, such differences may impact the provision (benefit) for income taxes in the period in which such determination is made. The Company records interest and penalties related to its uncertain tax positions in the provision (benefit) for income taxes. The establishment of deferred tax assets from intra-entity transfers of intangible assets requires management to make significant estimates and assumptions to determine the fair value of such intangible assets. Critical estimates in valuing the intangible assets include, but are not limited to, internal revenue and expense forecasts, the estimated life of the intangible assets, and discount rates. The discount rates used in the income method to discount expected future cash flows to present value are adjusted to reflect the inherent risks related to the cash flow. Although the Company believes the assumptions and estimates it has made are reasonable and appropriate, they are based, in part, on historical experience and are inherently uncertain. Unanticipated events and circumstances may occur that could affect either the accuracy or validity of such assumptions, estimates or actual results.
Foreign Currency	Foreign Currency The functional currency of the Company's foreign subsidiaries is generally the local currency. The financial statements of these subsidiaries are translated into U.S. dollars using period-end rates of exchange for assets and liabilities, historical rates of exchange for equity, and average rates of exchange for revenue and expenses. Translation gains (losses) are recorded in accumulated other comprehensive income (loss) as a component of stockholders’ equity. Unrealized foreign exchange gains and losses due to re-measurement of monetary assets and liabilities denominated in non-functional currencies as well as realized foreign exchange gains and losses on foreign exchange transactions are recorded in other income (expense), net in the accompanying consolidated statements of operations.
Advertising Costs	Advertising CostsAdvertising costs are expensed when incurred and are included in sales and marketing expense in the accompanying consolidated statements of operations.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) consists of two components, net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) refers to gains and losses that are recorded as an element of stockholders’ equity and are excluded from net income (loss). The Company’s other comprehensive income (loss) is comprised of unrealized gains or losses on available-for-sale securities, net of tax, and foreign currency translation adjustments.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted accounting pronouncements In June 2016, the Financial Accounting Standards Board (FASB) issued a new accounting standard update on the measurement of credit losses on financial instruments. The new guidance requires financial assets measured at amortized cost to be presented at the net amount expected to be collected and available-for-sale debt securities to record credit losses through an allowance for credit losses. The Company adopted this new accounting standard on January 1, 2020 using the modified retrospective method. In connection with the adoption of this guidance, the Company recorded a cumulative-effect adjustment of $1.6 million to opening retained earnings as of January 1, 2020, related to additional allowance for credit losses on doubtful accounts and unbilled revenue. In August 2018, the FASB issued a new accounting standard update which eliminates, adds and modifies certain disclosure requirements for fair value measurements. The update eliminates the requirement to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, and introduces a requirement to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The Company adopted this new accounting standard on January 1, 2020, using the prospective method, and the adoption did not have a material impact on the Company’s financial statements and related disclosures. In August 2018, the FASB issued a new accounting standard update requiring a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to capitalize certain implementation costs as if the arrangement was an internal-use software project. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The Company adopted the new accounting standard update on January 1, 2020, using the prospective method, and the adoption did not have a material impact on the Company’s financial statements and related disclosures. In December 2019, the FASB issued a new accounting standard update to simplify the accounting for income taxes. The new guidance removes certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocation and calculating income taxes in interim periods. It also adds guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. The Company adopted this guidance on January 1, 2020, using the modified retrospective method, and the adoption did not have a material impact on the Company's financial statements and related disclosures. Recently issued accounting pronouncements not yet adopted In August 2020, the FASB issued a new accounting standard update to simplify the accounting for convertible debt and other equity-linked instruments. The new guidance simplifies the accounting for convertible instruments by eliminating the cash conversion and beneficial conversion feature models used to separately account for embedded conversion features as a component of equity. Instead, the entity will account for the convertible debt or convertible preferred stock securities as a single unit of account, unless the conversion feature requires bifurcation and recognition as derivatives. Additionally, the guidance requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share calculation and include the effect of potential share settlement for instruments that may be settled in cash or shares. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021, using a modified or full retrospective transition method. Early adoption is permitted for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company will early adopt this new guidance using the modified retrospective method as of January 1, 2021. The adoption of this new guidance is estimated to result in an increase of approximately $255.0 million and $35.0 million to Convertible notes, long-term and Convertible notes, short-term, respectively, in the consolidated balance sheets, to reflect the full principal amount of the convertible notes outstanding net of issuance costs, a reduction of approximately $568.0 million to additional paid-in capital, net of estimated income tax effects, to remove the equity component separately recorded for the conversion features associated with the convertible notes, an increase to deferred tax assets, net of approximately $67.0 million, and a cumulative-effect adjustment of approximately $345.0 million, net of estimated income tax effects, to the beginning balance of accumulated deficit as of January 1, 2021. The adoption of this new guidance is anticipated to reduce interest expense by approximately $100.0 million during the year ended December 31, 2021. In addition, the required use of the if-converted method by the new guidance in calculating diluted earnings per share is expected to increase the number of potentially dilutive shares in 2021.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives of Property and Equipment	The estimated useful lives of property and equipment are described below: Property and Equipment Estimated Useful Life Computer hardware, networking and office equipment Three Computer software Up to five Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term The following tables set forth property and equipment, net by type and by geographic area for the periods presented (in thousands): December 31, December 31, Property and equipment, net Equipment $ 1,830,459 $ 1,445,003 Furniture and leasehold improvements 362,766 347,983 Capitalized software 811,371 688,894 Construction in progress 349,935 100,551 Total 3,354,531 2,582,431 Less: Accumulated depreciation and amortization (1,860,737) (1,550,650) Property and equipment, net $ 1,493,794 $ 1,031,781 December 31, December 31, Property and equipment, net: United States $ 1,460,163 $ 999,552 International 33,631 32,229 Total property and equipment, net $ 1,493,794 $ 1,031,781

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from External Customers by Products and Services	Revenue by geography is based on the billing address of the customers. The following tables set forth revenue by services and revenue by geographic area (in thousands): Year Ended December 31, 2020 2019 2018 Revenue by services: Advertising services $ 3,207,392 $ 2,993,392 $ 2,617,397 Data licensing and other 508,957 465,937 424,962 Total revenue $ 3,716,349 $ 3,459,329 $ 3,042,359
Revenue by Geographic Area	Year Ended December 31, 2020 2019 2018 Revenue by geographic area: United States $ 2,078,836 $ 1,944,022 $ 1,642,259 Japan 547,862 537,021 507,970 Rest of World 1,089,651 978,286 892,130 Total revenue $ 3,716,349 $ 3,459,329 $ 3,042,359
Summary of Contract Balances	The following table presents contract balances (in thousands): December 31, December 31, Unbilled Revenue $ 44,063 $ 27,691 Deferred Revenue $ 62,191 $ 69,000
Summary of Revenue Expected to Recognize on Remaining Performance Obligations Over the Time Periods	The Company expects to recognize this amount as revenue over the following time periods (in thousands): Remaining Performance Obligations 2021 2022 2023 and Thereafter Revenue expected to be recognized on remaining performance obligations $ 774,447 $ 299,300 $ 215,794 $ 259,353

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-term Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Cash, Cash and Equivalents and Short-term Investments	Cash, cash equivalents and short-term investments consist of the following (in thousands): December 31, December 31, Cash and cash equivalents: Cash $ 285,002 $ 254,405 Money market funds 1,158,927 465,158 Corporate notes, commercial paper and certificates of deposit 544,500 1,079,519 Total cash and cash equivalents $ 1,988,429 $ 1,799,082 Short-term investments: U.S. government and agency securities $ 910,259 $ 660,860 Corporate notes, commercial paper and certificates of deposit 4,572,394 4,179,110 Marketable equity securities 1,220 — Total short-term investments $ 5,483,873 $ 4,839,970
Contractual Maturities of Securities Classified as Available-for-Sale	The contractual maturities of debt securities classified as available-for-sale as of December 31, 2020 were as follows (in thousands): December 31, Due within one year $ 2,733,961 Due after one year through five years 2,748,692 Total $ 5,482,653
Summary of Unrealized Gains and Losses Related to Available-for-Sale Securities Classified as Short-term Investments	The following tables summarize unrealized gains and losses related to available-for-sale debt securities classified as short-term investments on the Company’s consolidated balance sheets (in thousands): December 31, 2020 Gross Gross Gross Aggregated U.S. government and agency securities $ 909,092 $ 1,177 $ (10) $ 910,259 Corporate notes, commercial paper and certificates of deposit 4,545,687 26,939 (232) 4,572,394 Total available-for-sale debt securities classified as short-term investments $ 5,454,779 $ 28,116 $ (242) $ 5,482,653 December 31, 2019 Gross Gross Gross Aggregated U.S. government and agency securities $ 660,361 $ 1,049 $ (550) $ 660,860 Corporate notes, commercial paper and certificates of deposit 4,166,203 13,133 (226) 4,179,110 Total available-for-sale debt securities classified as short-term investments $ 4,826,564 $ 14,182 $ (776) $ 4,839,970

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables set forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019 based on the three-tier fair value hierarchy (in thousands): December 31, 2020 Level 1 Level 2 Total Assets Cash equivalents: Money market funds $ 1,158,927 $ — $ 1,158,927 Corporate notes — 1,347 1,347 Commercial paper — 543,153 543,153 Short-term investments: U.S. government and agency securities — 910,259 910,259 Corporate notes — 2,829,521 2,829,521 Commercial paper — 1,240,670 1,240,670 Certificates of deposit — 502,203 502,203 Marketable equity securities 1,220 — 1,220 Other current assets: Foreign currency contracts — 5,529 5,529 Total $ 1,160,147 $ 6,032,682 $ 7,192,829 Liabilities Other current liabilities: Foreign currency contracts $ — $ 1,028 $ 1,028 Total $ — $ 1,028 $ 1,028 December 31, 2019 Level 1 Level 2 Total Assets Cash equivalents: Money market funds $ 465,158 $ — $ 465,158 Corporate notes — 8,246 8,246 Commercial paper — 1,031,825 1,031,825 Certificates of deposit — 39,448 39,448 Short-term investments: U.S. government and agency securities — 660,860 660,860 Corporate notes — 2,468,429 2,468,429 Commercial paper — 1,236,487 1,236,487 Certificates of deposit — 474,194 474,194 Other current assets: Foreign currency contracts — 3,756 3,756 Total $ 465,158 $ 5,923,245 $ 6,388,403 Liabilities Other current liabilities: Foreign currency contracts $ — $ 1,573 $ 1,573 Total $ — $ 1,573 $ 1,573
Schedule of Fair Values of Outstanding Derivative Instruments	The fair values of outstanding derivative instruments for the periods presented on a gross basis are as follows (in thousands): Balance Sheet Location December 31, December 31, Assets Foreign currency contracts not designated as hedging instruments Other current assets $ 5,529 $ 3,756 Liabilities Foreign currency contracts not designated as hedging instruments Other current liabilities $ 1,028 $ 1,573

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	The estimated useful lives of property and equipment are described below: Property and Equipment Estimated Useful Life Computer hardware, networking and office equipment Three Computer software Up to five Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term The following tables set forth property and equipment, net by type and by geographic area for the periods presented (in thousands): December 31, December 31, Property and equipment, net Equipment $ 1,830,459 $ 1,445,003 Furniture and leasehold improvements 362,766 347,983 Capitalized software 811,371 688,894 Construction in progress 349,935 100,551 Total 3,354,531 2,582,431 Less: Accumulated depreciation and amortization (1,860,737) (1,550,650) Property and equipment, net $ 1,493,794 $ 1,031,781 December 31, December 31, Property and equipment, net: United States $ 1,460,163 $ 999,552 International 33,631 32,229 Total property and equipment, net $ 1,493,794 $ 1,031,781

Operating and Finance Leases (T

Operating and Finance Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lease, Cost	The components of lease cost for the year ended December 31, 2020 were as follows (in thousands): Year Ended December 31, 2020 2019 Operating lease cost $ 201,386 $ 173,005 Finance lease cost Depreciation expense 20,527 63,674 Interest on lease liabilities 369 2,125 Total finance lease cost 20,896 65,799 Short-term lease cost 5,603 3,000 Variable lease cost 52,476 49,456 Sublease income (9,626) (22,326) Total lease cost $ 270,735 $ 268,934
Other Information Related To Leases	Other information related to leases was as follows (in thousands): Year Ended December 31, 2020 2019 Supplemental Cash Flows Information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 183,033 $ 165,093 Operating cash flows from finance leases $ 369 $ 2,125 Financing cash flows from finance leases $ 23,062 $ 66,677 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 398,480 $ 110,522 December 31, December 31, Lease Term and Discount Rate Weighted-average remaining lease term (years): Operating leases 6.8 6.6 Finance leases 0.1 0.7 Weighted-average discount rate: Operating leases 3.8 % 4.3 % Finance leases 3.9 % 3.7 %
Lessee, Operating Lease, Liability, Maturity	Future lease payments under leases and sublease income as of December 31, 2020 were as follows (in thousands): Operating Finance Total Sublease Year Ending December 31, 2021 $ 218,869 $ 569 $ 219,438 $ (8,976) 2022 251,548 — 251,548 (1,353) 2023 178,870 — 178,870 — 2024 178,669 — 178,669 — 2025 175,585 — 175,585 — Thereafter 667,742 — 667,742 — Total future lease payments (receipts) 1,671,283 569 1,671,852 $ (10,329) Less: leases not yet commenced (528,964) — (528,964) Less: imputed interest (145,424) (2) (145,426) Total lease liabilities $ 996,895 $ 567 $ 997,462 Reconciliation of lease liabilities as shown in the consolidated balance sheets Operating lease liabilities, short-term $ 177,147 $ — $ 177,147 Operating lease liabilities, long-term 819,748 — 819,748 Finance lease liabilities, short-term — 567 567 Total lease liabilities $ 996,895 $ 567 $ 997,462
Finance Lease, Liability, Maturity	Future lease payments under leases and sublease income as of December 31, 2020 were as follows (in thousands): Operating Finance Total Sublease Year Ending December 31, 2021 $ 218,869 $ 569 $ 219,438 $ (8,976) 2022 251,548 — 251,548 (1,353) 2023 178,870 — 178,870 — 2024 178,669 — 178,669 — 2025 175,585 — 175,585 — Thereafter 667,742 — 667,742 — Total future lease payments (receipts) 1,671,283 569 1,671,852 $ (10,329) Less: leases not yet commenced (528,964) — (528,964) Less: imputed interest (145,424) (2) (145,426) Total lease liabilities $ 996,895 $ 567 $ 997,462 Reconciliation of lease liabilities as shown in the consolidated balance sheets Operating lease liabilities, short-term $ 177,147 $ — $ 177,147 Operating lease liabilities, long-term 819,748 — 819,748 Finance lease liabilities, short-term — 567 567 Total lease liabilities $ 996,895 $ 567 $ 997,462

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill Activities	The following table presents the goodwill activities for the periods presented (in thousands): Goodwill Balance as of December 31, 2019 $ 1,256,699 Acquisitions 50,970 Other 4,677 Balance as of December 31, 2020 $ 1,312,346
Schedule of Intangible Assets	The following table presents the detail of intangible assets for the periods presented (in thousands): Gross Carrying Accumulated Net Carrying December 31, 2020: Patents and developed technologies $ 110,153 $ (53,265) $ 56,888 Other 1,800 (350) 1,450 Total $ 111,953 $ (53,615) $ 58,338 December 31, 2019: Patents and developed technologies $ 96,636 $ (41,530) $ 55,106 Total $ 96,636 $ (41,530) $ 55,106
Schedule of Estimated Future Amortization Expenses	Estimated future amortization expense as of December 31, 2020 is as follows (in thousands): 2021 $ 21,583 2022 14,528 2023 7,843 2024 6,026 2025 1,863 Thereafter 6,495 Total $ 58,338

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued and Other Liabilities	The following table presents the detail of accrued and other current liabilities for the periods presented (in thousands): December 31, December 31, Accrued compensation $ 171,681 $ 190,465 Federal Trade Commission accrual (see Note 16) 150,000 — Deferred revenue 58,976 68,987 Accrued publisher, content and ad network costs 42,541 45,265 Accrued tax liabilities 40,384 45,967 Accrued professional services 27,404 38,596 Accrued other 171,979 111,613 Total $ 662,965 $ 500,893

Senior Notes and Convertible _2

Senior Notes and Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Components of Notes	The Notes consisted of the following (in thousands): December 31, 2020 December 31, 2019 2021 Notes 2024 Notes 2025 Notes 2027 Notes 2021 Notes 2024 Notes 2027 Notes Principal amounts: Principal $ 954,000 $ 1,150,000 $ 1,000,000 $ 700,000 $ 954,000 $ 1,150,000 $ 700,000 Unamortized debt discount and issuance costs (1) (36,134) (160,297) (113,825) (7,006) (84,652) (202,515) (8,033) Net carrying amount $ 917,866 $ 989,703 $ 886,175 $ 692,994 $ 869,348 $ 947,485 $ 691,967 Carrying amount of the equity component (2) $ 283,283 $ 254,981 $ 121,413 $ — $ 283,283 $ 254,981 $ — (1) Included in the consolidated balance sheets within convertible notes, short-term; convertible notes, long-term; and senior notes, long-term, and amortized over the remaining lives of the Notes. (2) Included in the consolidated balance sheets within additional paid-in capital.

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net income (loss) per share for periods presented (in thousands, except per share data). Year Ended December 31, 2020 2019 2018 Basic net income (loss) per share: Numerator Net income (loss) $ (1,135,626) $ 1,465,659 $ 1,205,596 Denominator Weighted-average common shares outstanding 789,887 772,663 756,916 Weighted-average restricted stock subject to repurchase (2,026) (1,934) (2,590) Weighted-average shares used to compute basic net income (loss) per share 787,861 770,729 754,326 Basic net income (loss) per share attributable to common stockholders $ (1.44) $ 1.90 $ 1.60 Diluted net income (loss) per share: Numerator Net income (loss) $ (1,135,626) $ 1,465,659 $ 1,205,596 Denominator Number of shares used in basic computation 787,861 770,729 754,326 Weighted-average effect of dilutive securities: RSUs — 10,468 13,285 Stock options — 2,496 2,686 Other — 1,838 2,389 Weighted-average shares used to compute diluted net income (loss) per share 787,861 785,531 772,686 Diluted net income (loss) per share attributable to common stockholders $ (1.44) $ 1.87 $ 1.56
Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following potential common shares at the end of each period were excluded from the calculation of diluted net income (loss) per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands): Year Ended December 31, 2020 2019 2018 RSUs 36,611 12,117 14,949 Warrants 32,412 42,246 44,454 Stock options 1,436 3 837 Shares subject to repurchase and others 5,668 1,284 1,951

Common Stock and Stockholders_2

Common Stock and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Restricted Stock Activity	The activities for the restricted common stock issued to employees for the year ended December 31, 2020 are summarized as follows (in thousands, except per share data): Number of Weighted-Average Unvested restricted common stock at December 31, 2019 1,428 $ 24.26 Granted 1,677 $ 32.90 Vested (1,107) $ 20.66 Unvested restricted common stock at December 31, 2020 1,998 $ 34.00
Summary of Stock Option Activity	A summary of stock option activity for the year ended December 31, 2020 is as follows (in thousands, except years and per share data): Options Outstanding Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2019 3,227 $ 9.84 2.65 $ 74,630 Options granted and assumed in connection with acquisitions 128 $ 7.08 Options exercised (1,882) $ 2.89 Options canceled (37) $ 0.91 Outstanding at December 31, 2020 1,436 $ 18.97 3.39 $ 50,534 Exercisable at December 31, 2020 1,415 $ 18.87 3.32 $ 49,932
Summary of RSU Activity	The following table summarizes the activity related to the Company’s RSUs, excluding PRSUs and TSR RSUs, for the year ended December 31, 2020. For purposes of this table, vested RSUs represent the shares for which the service condition had been fulfilled as of each respective date (in thousands, except per share data): RSUs Outstanding Shares Weighted- Unvested and outstanding at December 31, 2019 31,731 $ 29.74 Granted 23,795 $ 32.24 Vested (15,768) $ 27.41 Canceled (3,147) $ 30.78 Unvested and outstanding at December 31, 2020 36,611 $ 32.28
Compensation Expense Allocated	Total stock-based compensation expense by function is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Cost of revenue $ 32,020 $ 22,797 $ 17,289 Research and development 281,092 209,063 183,799 Sales and marketing 98,748 85,739 71,305 General and administrative 63,072 60,426 53,835 Total stock-based compensation expense $ 474,932 $ 378,025 $ 326,228
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of RSU Activity	The following table summarizes the activity related to the Company’s PRSUs for the year ended December 31, 2020 (in thousands, except per share data): PRSUs Outstanding Shares Weighted- Unvested and outstanding at December 31, 2019 646 $ 31.52 Granted (100% target level) 729 $ 27.77 Vested (100% target level) (646) $ 31.52 Unvested and outstanding at December 31, 2020 729 $ 27.77
TSR RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of RSU Activity	The following table summarizes the activity related to the Company’s TSR RSUs for the year ended December 31, 2020 (in thousands, except per share data): TSR RSUs Outstanding Shares Weighted- Unvested and outstanding at December 31, 2019 759 $ 41.15 Granted (100% target level) 487 $ 31.16 Additional earned performance shares related to 2019 grants 52 $ 54.97 Vested (116% target level) (381) $ 54.97 Unvested and outstanding at December 31, 2020 917 $ 30.90

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summary of Domestic and Foreign Components of Income (Loss) Before Income Taxes	The domestic and foreign components of income (loss) before income taxes for the years ended December 31, 2020, 2019 and 2018 are as follows (in thousands): Year Ended December 31, 2020 2019 2018 Domestic $ (72,850) $ 317,135 $ 193,500 Foreign 21,911 73,004 230,044 Income (loss) before income taxes $ (50,939) $ 390,139 $ 423,544
Components of Provision (Benefit) for Income Taxes	The components of the provision (benefit) for income taxes for the years ended December 31, 2020, 2019 and 2018 are as follows (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ (199) $ 563 $ (1,661) State 677 3,375 4,083 Foreign 19,813 43,053 17,246 Total current provision for income taxes 20,291 46,991 19,668 Deferred: Federal (35,651) 2,023 (711,084) State (2,248) 2,050 (49,047) Foreign 1,102,295 (1,126,584) (41,589) Total deferred provision (benefit) for income taxes 1,064,396 (1,122,511) (801,720) Provision (benefit) for income taxes $ 1,084,687 $ (1,075,520) $ (782,052)
Schedule of Reconciliation of Statutory Federal Income Tax Rate to Effective Tax Rate	The following is a reconciliation of the income tax at the federal statutory rate to the Company’s provision (benefit) for income taxes for the years ended December 31, 2020, 2019 and 2018 (in thousands): Year Ended December 31, 2020 2019 2018 Income tax at federal statutory rate $ (10,697) 81,929 $ 88,944 State taxes, net of federal benefit (1,246) 4,286 (35,521) Stock-based compensation (27,127) (19,005) (27,228) Research and development credits (40,707) (33,044) (23,490) Valuation allowance 1,104,732 (724) (758,707) Nondeductible other expenses 7,438 12,266 682 Nondeductible Federal Trade Commission settlement accrual 31,500 — — Deferred tax asset on intra-entity transfer of intangible assets — (1,203,381) — Foreign rate differential 22,078 79,186 (27,002) Other (1,284) 2,967 270 Provision (benefit) for income taxes $ 1,084,687 $ (1,075,520) $ (782,052)
Schedule of Tax Effects of Temporary Differences and Related Deferred Tax Assets and Liabilities	The tax effects of temporary differences and related deferred tax assets and liabilities as of December 31, 2020 and 2019 are as follows (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 421,411 $ 390,005 Tax credits 485,106 425,011 Fixed assets and intangible assets 1,280,597 1,214,070 Operating lease liability 230,837 170,817 Other 82,596 90,115 Total deferred tax assets 2,500,547 2,290,018 Valuation allowance (1,457,137) (223,775) Total deferred tax assets, net of valuation allowance 1,043,410 2,066,243 Deferred tax liabilities: Operating lease right-of-use asset (215,663) (157,845) Other (32,451) (1,138) Total deferred tax liabilities (248,114) (158,983) Net deferred tax assets $ 795,296 $ 1,907,260
Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit	A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Gross unrecognized tax benefits at the beginning of the year $ 419,858 $ 332,314 $ 259,781 Increases related to prior year tax positions 5,943 54,743 20,000 Decreases related to prior year tax positions (99,540) (2,537) (13,174) Increases related to current year tax positions 28,337 35,338 66,249 Statute of limitations expirations — — (542) Gross unrecognized tax benefits at the end of the year $ 354,598 $ 419,858 $ 332,314
Summary of Unrecognized Tax Benefits Recorded in Balance Sheet	Total unrecognized tax benefits are recorded on the Company’s consolidated balance sheets as follows (in thousands): December 31, 2020 2019 Total unrecognized tax benefits balance $ 354,598 $ 419,858 Amounts netted against related deferred tax assets (331,339) (401,818) Unrecognized tax benefits recorded on consolidated balance sheets $ 23,259 $ 18,040

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Summary of Commitments to Settle Contractual Obligations in Cash	The following table summarizes its commitments to settle contractual obligations in cash as of December 31, 2020: Payments Due by Year Total 2021 2022-2023 2024-2025 Thereafter (In thousands) 2021 Notes $ 963,540 $ 963,540 $ — $ — $ — 2024 Notes 1,160,039 2,867 5,734 1,151,438 — 2025 Notes 1,016,825 3,740 7,480 1,005,605 — 2027 Notes 889,819 27,106 54,213 54,287 754,213 Operating lease obligations (1) 1,671,283 218,869 430,418 354,254 667,742 Finance lease obligations 569 569 — — — Other contractual commitments (2) 1,669,012 227,601 519,866 734,827 186,718 Total contractual obligations $ 7,371,087 $ 1,444,292 $ 1,017,711 $ 3,300,411 $ 1,608,673 (1) The Company has entered into several sublease agreements for office space that it is not fully utilizing. Under the sublease agreements, the Company will receive approximately $10.3 million in sublease income over the next two years. (2) Other contractual commitments are non-cancelable contractual commitments primarily related to the Company’s infrastructure services and other services arrangements.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Jan. 01, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Cash, cash equivalents, and short-term investments			$ 7,470,000,000
Interest earned on cash, cash equivalent and marketable securities			88,178,000	$ 157,703,000	$ 111,221,000
Allowance for credit loss, period increase (decrease)			17,200,000
Allowance for credit loss, writeoff			2,700,000
Capitalized interest expenses			3,800,000	4,600,000	3,700,000
Impairment charges on goodwill			$ 0	0	0
Intangible assets, estimated useful lives			11 years
Impairment charges on intangible assets			$ 0	0	0
Software developing program costs capitalized			$ 109,300,000	127,500,000	121,000,000
Capitalized computer software, useful life			5 years
Amortization of capitalized costs			$ 109,600,000	116,000,000	111,800,000
Advertising expense			56,100,000	81,300,000	80,800,000
Cumulative-effect adjustment from ASU adoption			(7,970,082,000)	(8,704,386,000)	(6,805,594,000)
Operating lease right-of-use assets			930,139,000	697,095,000
Operating Lease, Liability			996,895,000
Increase (decrease) in convertible notes payable, noncurrent			1,875,878,000	1,816,833,000
Increase (decrease) in convertible notes Payable, current			917,866,000	0
Accumulated deficit			(1,125,669,000)	11,586,000
Interest expense			$ (152,878,000)	(138,180,000)	(132,606,000)
Service-Based Restricted Stock
Significant Accounting Policies [Line Items]
Vesting condition period			5 years
Forecast
Significant Accounting Policies [Line Items]
Increase (decrease) in convertible notes payable, noncurrent	$ 255,000,000
Increase (decrease) in convertible notes Payable, current	35,000,000
Decrease in equity component of the convertible note issuance, net	568,000,000
Deferred tax asset, increase (decrease), amount	67,000,000
Interest expense		$ (100,000,000)
Retained earnings (accumulated deficit)
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment from ASU adoption			$ 1,125,669,000	(11,586,000)	1,454,073,000	$ 2,671,729,000
Cumulative Effect, Period of Adoption, Adjustment | Forecast
Significant Accounting Policies [Line Items]
Accumulated deficit	$ 345,000,000
Cumulative Effect, Period of Adoption, Adjustment | Retained earnings (accumulated deficit)
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment from ASU adoption				1,629,000		$ (12,060,000)
Internal Use Software and Website Development Costs
Significant Accounting Policies [Line Items]
Share-based compensation, capitalized amount			$ 34,600,000	$ 37,500,000	$ 41,400,000
Customer Concentration Risk | Accounts Receivable
Significant Accounting Policies [Line Items]
Concentration risk percentage			10.00%	10.00%	10.00%
Customer Concentration Risk | Revenue
Significant Accounting Policies [Line Items]
Concentration risk percentage			10.00%	10.00%	10.00%
Prepaid Expenses and Other Current Assets
Significant Accounting Policies [Line Items]
Restricted cash balances			$ 2,300,000	$ 1,900,000
Other assets
Significant Accounting Policies [Line Items]
Restricted cash balances			$ 20,600,000	$ 26,700,000
Maximum
Significant Accounting Policies [Line Items]
Finance lease, term of contract			4 years
Maximum | Performance-Based and Market-Based Restricted Stock Award
Significant Accounting Policies [Line Items]
Vesting condition period			3 years
Minimum
Significant Accounting Policies [Line Items]
Finance lease, term of contract			3 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Computer hardware, networking and office equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer hardware, networking and office equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Computer software
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life		5 years

Revenue - Revenue by Services a

Revenue - Revenue by Services and Revenue by Products and Services (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Revenue	$ 3,716,349	$ 3,459,329	$ 3,042,359
United States
Revenue:
Revenue	2,078,836	1,944,022	1,642,259
Japan
Revenue:
Revenue	547,862	537,021	507,970
Rest of World
Revenue:
Revenue	1,089,651	978,286	892,130
Advertising services
Revenue:
Revenue	3,207,392	2,993,392	2,617,397
Data licensing and other
Revenue:
Revenue	$ 508,957	$ 465,937	$ 424,962

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Deferred revenue, revenue recognized	$ 69,000	$ 38,900
Aggregate amount of transaction price allocated to remaining performance obligations	774,447
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in unbilled revenue	44,063	27,691
Deferred Revenue	62,191	69,000
Revenue	$ 3,716,349	$ 3,459,329	$ 3,042,359

Revenue - Summary of Contract B

Revenue - Summary of Contract Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues [Abstract]
Increase in unbilled revenue	$ 44,063	$ 27,691
Deferred Revenue	$ 62,191	$ 69,000

Revenue - Summary of Revenue Ex

Revenue - Summary of Revenue Expected to Recognize on Remaining Performance Obligations Over the Time Periods (Details) $ in Thousands	Dec. 31, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized on remaining performance obligations	$ 774,447
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized on remaining performance obligations	$ 299,300
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized on remaining performance obligations	$ 215,794
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized on remaining performance obligations	$ 259,353
Revenue, remaining performance obligation, expected timing of satisfaction, period

Cash, Cash Equivalents and Sh_3

Cash, Cash Equivalents and Short-term Investments - Cash, Cash and Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash and cash equivalents:
Cash	$ 285,002	$ 254,405
Cash and Cash Equivalents	1,988,429	1,799,082	$ 1,894,444
Short-term investments:
Short-term investments	5,482,653	4,839,970
Marketable equity securities	1,220	0
Short-term Investments	5,483,873	4,839,970
Money market funds
Cash and cash equivalents:
Cash and Cash Equivalents	1,158,927	465,158
U.S. government and agency securities
Short-term investments:
Short-term investments	910,259	660,860
Corporate notes, commercial paper and certificates of deposit
Cash and cash equivalents:
Cash and Cash Equivalents	544,500	1,079,519
Short-term investments:
Short-term investments	$ 4,572,394	$ 4,179,110

Cash, Cash Equivalents and Sh_4

Cash, Cash Equivalents and Short-term Investments - Contractual Maturities of Securities Classified as Available-for-Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash And Cash Equivalents And Marketable Securities [Abstract]
Due within one year	$ 2,733,961
Due after one year through five years	2,748,692
Total	$ 5,482,653	$ 4,839,970

Cash, Cash Equivalents and Sh_5

Cash, Cash Equivalents and Short-term Investments - Summary of Unrealized Gains and Losses Related to Available-for-Sale Securities Classified as Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	$ 5,454,779	$ 4,826,564
Gross Unrealized Gains	28,116	14,182
Gross Unrealized Losses	(242)	(776)
Aggregated Estimated Fair Value	5,482,653	4,839,970
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	909,092	660,361
Gross Unrealized Gains	1,177	1,049
Gross Unrealized Losses	(10)	(550)
Aggregated Estimated Fair Value	910,259	660,860
Corporate notes, commercial paper and certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	4,545,687	4,166,203
Gross Unrealized Gains	26,939	13,133
Gross Unrealized Losses	(232)	(226)
Aggregated Estimated Fair Value	$ 4,572,394	$ 4,179,110

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	$ 5,482,653	$ 4,839,970
Marketable equity securities	1,220	0
Other current assets	5,529	3,756
Other current liabilities	1,028	1,573
Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Marketable equity securities	1,220
Total	7,192,829	6,388,403
Financial and Nonfinancial Liabilities, Fair Value Disclosure	1,028	1,573
Fair Value, Measurements, Recurring | Money market funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	1,158,927	465,158
Fair Value, Measurements, Recurring | Corporate notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	1,347	8,246
Short-term investments	2,829,521	2,468,429
Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	543,153	1,031,825
Short-term investments	1,240,670	1,236,487
Fair Value, Measurements, Recurring | Certificates of deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		39,448
Short-term investments	502,203	474,194
Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	910,259	660,860
Fair Value, Measurements, Recurring | Foreign currency contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	5,529	3,756
Other current liabilities	1,028	1,573
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Marketable equity securities	1,220
Total	1,160,147	465,158
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Level 1 | Fair Value, Measurements, Recurring | Money market funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	1,158,927	465,158
Level 1 | Fair Value, Measurements, Recurring | Corporate notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	0	0
Short-term investments	0	0
Level 1 | Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	0	0
Short-term investments	0	0
Level 1 | Fair Value, Measurements, Recurring | Certificates of deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		0
Short-term investments	0	0
Level 1 | Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	0	0
Level 1 | Fair Value, Measurements, Recurring | Foreign currency contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	0	0
Other current liabilities	0	0
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Marketable equity securities	0
Total	6,032,682	5,923,245
Financial and Nonfinancial Liabilities, Fair Value Disclosure	1,028	1,573
Level 2 | Fair Value, Measurements, Recurring | Money market funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	0	0
Level 2 | Fair Value, Measurements, Recurring | Corporate notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	1,347	8,246
Short-term investments	2,829,521	2,468,429
Level 2 | Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	543,153	1,031,825
Short-term investments	1,240,670	1,236,487
Level 2 | Fair Value, Measurements, Recurring | Certificates of deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		39,448
Short-term investments	502,203	474,194
Level 2 | Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	910,259	660,860
Level 2 | Fair Value, Measurements, Recurring | Foreign currency contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	5,529	3,756
Other current liabilities	$ 1,028	$ 1,573

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional principal of foreign currency contracts outstanding	$ 729,800,000	$ 456,100,000
Net gain (losses) on foreign currency contracts	(8,100,000)	7,200,000	$ 11,600,000
Senior Notes | Senior Notes Due 2027
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 700,000,000	$ 700,000,000
Debt Instrument, percentage	3.875%	3.875%
Senior Notes | Level 2 | Senior Notes Due 2027
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, fair value disclosure	$ 745,500,000
Convertible Notes | Convertible Notes Due 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 954,000,000				$ 954,000,000
Debt Instrument, percentage	1.00%				1.00%
Convertible Notes | Convertible Notes Due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 1,150,000,000		$ 1,150,000,000
Debt Instrument, percentage	0.25%		0.25%
Convertible Notes | Convertible Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 1,000,000,000			$ 1,000,000,000
Debt Instrument, percentage	0.375%			0.375%
Convertible Notes | Level 2 | Convertible Notes Due 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, fair value disclosure	$ 975,300,000
Convertible Notes | Level 2 | Convertible Notes Due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, fair value disclosure	1,390,000,000
Convertible Notes | Fair Value, Inputs, Level 3 [Member] | Convertible Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of notes based on a market approach	$ 1,450,000,000

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Fair Values of Outstanding Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	$ 5,529	$ 3,756
Liabilities, Fair Value Disclosure [Abstract]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	$ 1,028	$ 1,573

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property and equipment, net
Property and equipment, gross	$ 3,354,531	$ 2,582,431
Less: Accumulated depreciation and amortization	(1,860,737)	(1,550,650)
Property and equipment, net	1,493,794	1,031,781
Equipment
Property and equipment, net
Property and equipment, gross	1,830,459	1,445,003
Furniture and leasehold improvements
Property and equipment, net
Property and equipment, gross	362,766	347,983
Capitalized software
Property and equipment, net
Property and equipment, gross	811,371	688,894
Construction in progress
Property and equipment, net
Property and equipment, gross	$ 349,935	$ 100,551

Property and Equipment, Net - B

Property and Equipment, Net - By Geographic (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property and equipment, net:
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	$ 1,493,794	$ 1,031,781
United States
Property and equipment, net:
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	1,460,163	999,552
International
Property and equipment, net:
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	$ 33,631	$ 32,229

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	$ 471,600	$ 449,000	$ 406,500
Depreciation expense	20,527	63,674
Computer hardware, networking and office equipment
Property, Plant and Equipment [Line Items]
Depreciation expense			$ 84,200
Depreciation expense	$ 20,500	$ 63,700

Operating and Finance Leases (D

Operating and Finance Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Line Items]
Assets recorded under finance leases	$ 13.3	$ 126
Accumulated depreciation associated with finance leases	$ 12.8	$ 104.2
Maximum
Leases [Line Items]
Remaining lease term	10 years
Minimum
Leases [Line Items]
Remaining lease term	1 year

Operating and Finance Leases -

Operating and Finance Leases - Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Cost	$ 201,386	$ 173,005
Finance Lease Costs [Abstract]
Depreciation expense	20,527	63,674
Interest on lease liabilities	369	2,125
Total finance lease cost	20,896	65,799
Short-term lease cost	5,603	3,000
Variable lease cost	52,476	49,456
Sublease income	(9,626)	(22,326)
Total lease cost	$ 270,735	$ 268,934

Operating and Finance Leases _2

Operating and Finance Leases - Summary of Other Information Related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 183,033	$ 165,093
Operating cash flows from finance leases	369	2,125
Financing cash flows from finance leases	23,062	66,677	$ 90,351
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 398,480	$ 110,522
Weighted-average remaining lease term (years):
Operating leases	6 years 9 months 18 days	6 years 7 months 6 days
Finance leases	1 month 6 days	8 months 12 days
Weighted-average discount rate:
Operating leases	3.80%	4.30%
Finance leases	3.90%	3.70%

Operating and Finance Leases _3

Operating and Finance Leases - Summary of Future Lease Payments under Leases and Sublease Income (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
2021	$ 218,869
2022	251,548
2023	178,870
2024	178,669
2025	175,585
Thereafter	667,742
Total future lease payments (receipts)	1,671,283
Less: leases not yet commenced	(528,964)
Less: imputed interest	(145,424)
Total lease liabilities	996,895
Finance Leases
2021	569
2022	0
2023	0
2024	0
2025	0
Thereafter	0
Total future lease payments (receipts)	569
Less: leases not yet commenced	0
Less: imputed interest	(2)
Total lease liabilities	567
Total
2021	219,438
2022	251,548
2023	178,870
2024	178,669
2025	175,585
Thereafter	667,742
Total future lease payments (receipts)	1,671,852
Less: leases not yet commenced	(528,964)
Less: imputed interest	(145,426)
Total lease liabilities	997,462
Sublease Income
2021	(8,976)
2022	(1,353)
2023	0
2024	0
2025	0
Thereafter	0
Total	(10,329)
Reconciliation Of Lease Liabilities [Abstract]
Operating lease liabilities, short-term	177,147	$ 146,959
Operating lease liabilities, long-term	819,748	609,245
Total lease liabilities	996,895
Finance lease liabilities, short-term	567	$ 23,476
Total lease liabilities	567
Total lease liabilities	$ 997,462

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Schedule of Goodwill Activities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Goodwill
Beginning balance	$ 1,256,699
Acquisitions	50,970
Other	4,677
Ending balance	$ 1,312,346

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Impairment charges on goodwill	$ 0	$ 0	$ 0
Intangible assets, estimated useful lives	11 years
Amortization of intangible assets	$ 23,600,000	$ 16,500,000	$ 19,000,000
Fully amortized finite lived intangible assets	$ 11,500,000
Patents and developed technologies
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	11 years

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 111,953	$ 96,636
Accumulated Amortization	(53,615)	(41,530)
Total	58,338	55,106
Patents and developed technologies
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	110,153	96,636
Accumulated Amortization	(53,265)	(41,530)
Total	56,888	$ 55,106
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,800
Accumulated Amortization	(350)
Total	$ 1,450

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Schedule of Estimated Future Amortization Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 21,583
2022	14,528
2023	7,843
2024	6,026
2025	1,863
Thereafter	6,495
Total	$ 58,338	$ 55,106

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued compensation	$ 171,681	$ 190,465
Federal Trade Commission accrual	150,000	0
Deferred revenue	58,976	68,987
Accrued publisher, content and ad network costs	42,541	45,265
Accrued tax liabilities	40,384	45,967
Accrued professional services	27,404	38,596
Accrued other	171,979	111,613
Total	$ 662,965	$ 500,893

Acquisitions and Other Invest_2

Acquisitions and Other Investments - Acquisitions, Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Intangible assets, estimated useful lives	11 years
Acquisitions	$ 50,970,000
Other Expense
Business Acquisition [Line Items]
Gain on sale of investments	0	$ 10,200,000	$ 0
Other acquisitions
Business Acquisition [Line Items]
Consideration transferred	69,700,000	34,500,000	53,700,000
Purchase price cash consideration		29,900,000	34,600,000
Indemnification holdback		4,600,000
Liabilities		(1,900,000)
Acquisitions	51,000,000	27,400,000	44,000,000
Business acquisition, common stock issued			19,100,000
Acquisition purchase price allocated to assets	4,900,000		400,000
Other acquisitions | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	$ 13,800,000	$ 9,000,000	$ 9,300,000
Intangible assets, estimated useful lives	3 years	3 years	2 years

Acquisitions and Other Invest_3

Acquisitions and Other Investments - Investments in Privately-Held Companies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Carrying value of investments	$ 85,800,000	$ 77,700,000
Impairment charge	8,842,000	1,550,000	$ 3,000,000
Investments in Privately-Held Companies
Schedule of Investments [Line Items]
Financing receivable, loan in process	60,000,000
Other Expense
Schedule of Investments [Line Items]
Impairment charge	8,800,000	1,600,000	3,000,000
Gain on sale of investments	$ 0	$ 10,200,000	$ 0

Senior Notes and Convertible _3

Senior Notes and Convertible Notes - Additional Information (Details) $ / shares in Units, shares in Millions	1 Months Ended			12 Months Ended
	Mar. 31, 2020USD ($)d$ / shares	Dec. 31, 2019USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2020USD ($)dD$ / shares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2014USD ($)	Jun. 30, 2019$ / sharesshares	Dec. 31, 2015$ / shares
Debt Instrument [Line Items]
Convertible notes, long-term		$ 1,816,833,000		$ 1,875,878,000	$ 1,816,833,000
Proceeds from issuance of warrants concurrent with note hedges				0	0	$ 186,760,000
Amortization of debt discount, prior to capitalization of interest				112,200,000	123,600,000	115,400,000
Debt instrument coupon interest expense				42,600,000	15,700,000	13,400,000
Repayment of convertible notes				$ 0	(935,000,000)	0
2021 Notes
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares				$ 77.64
Exercise price of the warrants (in dollars per share) | $ / shares				105.28
2024 Notes
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares				57.14
Exercise price of the warrants (in dollars per share) | $ / shares				80.20
Convertible Notes Due 2025
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares				$ 41.50
Senior Notes | Senior Notes Due 2027
Debt Instrument [Line Items]
Debt instrument, principal amount		$ 700,000,000		$ 700,000,000	$ 700,000,000
Debt instrument, interest rate percentage		3.875%		3.875%	3.875%
Debt issuance costs		$ 8,100,000			$ 8,100,000
Price percentage for repurchase of notes if repurchase option is elected		101.00%
Percentage of principal amount redeemed		100.00%
Proceeds from offerings, net of transaction costs		$ 691,900,000
Convertible Notes
Debt Instrument [Line Items]
Exercise price of the warrants (in dollars per share) | $ / shares									$ 105.28
Convertible Notes | 2021 Notes
Debt Instrument [Line Items]
Debt instrument, principal amount				$ 954,000,000			$ 954,000,000
Debt instrument, interest rate percentage				1.00%			1.00%
Debt issuance costs							$ 200,000
Proceeds from offerings, net of transaction costs							939,500,000
Carrying amount of the equity component				$ 283,300,000
Effective interest rate for amortization to interest expense				6.25%
Debt discount							$ 14,300,000
Number of shares authorized for repurchase under hedge agreement | shares								12.3
Purchases of convertible note hedges			$ 233,500,000
Number of warrants issued | shares								12.3
Proceeds from issuance of warrants concurrent with note hedges			172,900,000
Remaining period for convertible debt				8 months
Convertible Notes | 2021 Notes | Common Stock
Debt Instrument [Line Items]
Debt Instrument, conversion ratio				0.0128793
Conversion price (in dollars per share) | $ / shares				$ 77.64
Convertible Notes | 2024 Notes
Debt Instrument [Line Items]
Debt instrument, principal amount				$ 1,150,000,000		$ 1,150,000,000
Debt instrument, interest rate percentage				0.25%		0.25%
Debt issuance costs						$ 12,300,000
Conversion price (in dollars per share) | $ / shares				$ 57.14
Price percentage for repurchase of notes if repurchase option is elected				100.00%
Proceeds from offerings, net of transaction costs						$ 1,140,000,000
Carrying amount of the equity component				$ 255,000,000
Effective interest rate for amortization to interest expense				4.46%
Number of shares authorized for repurchase under hedge agreement | shares								20.1
Purchases of convertible note hedges			268,000,000
Number of warrants issued | shares								20.1
Exercise price of the warrants (in dollars per share) | $ / shares				$ 80.20				$ 80.20
Proceeds from issuance of warrants concurrent with note hedges			$ 186,800,000
Remaining period for convertible debt				41 months
Convertible Notes | 2024 Notes | Scenario One
Debt Instrument [Line Items]
Convertible debt instrument, percentage of conversion price to trigger conversion to common stock				130.00%
Convertible debt instrument, consecutive trading days threshold | d				30
Convertible Notes | 2024 Notes | Scenario One | Minimum
Debt Instrument [Line Items]
Convertible debt instrument, trading days threshold | d				20
Convertible Notes | 2024 Notes | Scenario Two
Debt Instrument [Line Items]
Convertible debt instrument, trading days threshold | D				5
Convertible debt instrument, percentage of conversion price to trigger conversion to common stock				98.00%
Convertible debt instrument, consecutive trading days threshold | D				5
Convertible Notes | 2024 Notes | Common Stock
Debt Instrument [Line Items]
Debt Instrument, conversion ratio				0.0175001
Conversion price (in dollars per share) | $ / shares				$ 57.14
Convertible Notes | Convertible Notes 2021 and 2024
Debt Instrument [Line Items]
Equity component of the convertible note issuance, net				$ 2,800,000
Amortization of discount on convertible notes				9,800,000
Convertible Notes | Convertible Notes Due 2025
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 1,000,000,000			$ 1,000,000,000
Debt instrument, interest rate percentage	0.375%			0.375%
Debt issuance costs	$ 14,700,000
Convertible debt instrument, trading days threshold | d	20
Convertible debt instrument, percentage of conversion price to trigger conversion to common stock	130.00%
Convertible debt instrument, consecutive trading days threshold | d	30
Price percentage for repurchase of notes if repurchase option is elected	100.00%
Proceeds from offerings, net of transaction costs	$ 985,300,000
Carrying amount of the equity component	$ 121,400,000
Effective interest rate for amortization to interest expense	2.99%
Equity component of the convertible note issuance, net	$ 1,800,000
Amortization of discount on convertible notes	$ 12,900,000
Remaining period for convertible debt				50 months
Convertible Notes | Convertible Notes Due 2025 | Common Stock
Debt Instrument [Line Items]
Debt Instrument, conversion ratio	0.0240964
Conversion price (in dollars per share) | $ / shares	$ 41.50
Senior Loans | Senior Notes Due 2027
Debt Instrument [Line Items]
Remaining period for convertible debt				83 months

Senior Notes and Convertible _4

Senior Notes and Convertible Notes - Components of Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Principal amounts:
Net carrying amount	$ 917,866	$ 0
2021 Notes | Convertible Notes
Principal amounts:
Debt instrument, principal amount	954,000	954,000
Unamortized debt discount and issuance costs	(36,134)	(84,652)
Net carrying amount	917,866	869,348
Carrying amount of the equity component	283,283	283,283
2024 Notes | Convertible Notes
Principal amounts:
Debt instrument, principal amount	1,150,000	1,150,000
Unamortized debt discount and issuance costs	(160,297)	(202,515)
Net carrying amount	989,703	947,485
Carrying amount of the equity component	254,981	254,981
Convertible Notes Due 2025 | Convertible Notes
Principal amounts:
Debt instrument, principal amount	1,000,000
Unamortized debt discount and issuance costs	(113,825)
Net carrying amount	886,175
Carrying amount of the equity component	121,413
Senior Notes Due 2027 | Senior Notes
Principal amounts:
Debt instrument, principal amount	700,000	700,000
Unamortized debt discount and issuance costs	(7,006)	(8,033)
Net carrying amount	692,994	691,967
Carrying amount of the equity component	$ 0	$ 0

Net Income (Loss) Per Share - B

Net Income (Loss) Per Share - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator
Net income (loss)	$ (1,135,626)	$ 1,465,659	$ 1,205,596
Denominator
Weighted-average common shares outstanding	789,887	772,663	756,916
Weighted-average restricted stock subject to repurchase	(2,026)	(1,934)	(2,590)
Weighted-average shares used to compute basic net income (loss) per share	787,861	770,729	754,326
Basic (in dollars per share)	$ (1.44)	$ 1.90	$ 1.60
Numerator
Net income (loss)	$ (1,135,626)	$ 1,465,659	$ 1,205,596
Denominator
Number of shares used in basic computation	787,861	770,729	754,326
Weighted-average effect of dilutive securities:
RSUs	0	10,468	13,285
Stock options	0	2,496	2,686
Other	0	1,838	2,389
Weighted-average shares used to compute diluted net income (loss) per share	787,861	785,531	772,686
Diluted (in dollars per share)	$ (1.44)	$ 1.87	$ 1.56

Net Income (Loss) Per Share - S

Net Income (Loss) Per Share - Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
RSUs
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	36,611	12,117	14,949
Warrants
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	32,412	42,246	44,454
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	1,436	3	837
Shares subject to repurchase and others
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	5,668	1,284	1,951

Net Income (Loss) Per Share - A

Net Income (Loss) Per Share - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020$ / sharesshares
2024 Notes
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Conversion price (in dollars per share)	$ 57.14
Conversion spread will have a dilutive impact on diluted net income per share of common stock | shares	20,100,000
Exercise price of the warrants (in dollars per share)	$ 80.20
Convertible Notes Due 2025
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Conversion price (in dollars per share)	$ 41.50
Conversion spread will have a dilutive impact on diluted net income per share of common stock | shares	24,100,000
2021 Notes
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Conversion price (in dollars per share)	$ 77.64
Conversion spread will have a dilutive impact on diluted net income per share of common stock | shares	12,300,000
Exercise price of the warrants (in dollars per share)	$ 105.28

Preferred Stock - Additional In

Preferred Stock - Additional Information (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Features of Convertible Preferred Stock [Abstract]
Preferred shares, authorized (in shares)	200,000,000	200,000,000
Preferred shares, outstanding (in shares)	0	0

Common Stock and Stockholders_3

Common Stock and Stockholders' Equity - Additional Information (Details) - USD ($)	Nov. 07, 2013	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares, authorized (in shares)		5,000,000,000	5,000,000,000
Common stock, par value (in dollars per share)		$ 0.000005	$ 0.000005
Dividends declared		$ 0
Stock options outstanding		1,436,000	3,227,000
Options granted expire years		10 years
Number of shares authorized to be repurchased (in shares)					2,000,000,000
Repurchased of common stock, shares		5,700,000
Repurchases of common stock		$ 250,600,000
Treasury stock (in shares)		98,000	0
Treasury stock, value		$ 5,297,000	$ 0
Issuance of common stock upon purchases under employee stock purchase plan, shares		2,300,000	1,600,000
Employee stock purchase plan (ESOP), weighted average purchase price of shares purchased		$ 24.65	$ 26.62
Gross unamortized stock-based compensation expense related to unvested awards		$ 1,140,000,000
Unrecognized share-based compensation expense, weighted average recognition period		2 years 8 months 12 days
Internal Use Software and Website Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, capitalized amount		$ 34,600,000	$ 37,500,000	$ 41,400,000
Restricted Common Stock | All Acquisitions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity compensation service period		4 years
Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised, intrinsic value		$ 78,500,000	13,100,000	16,900,000
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock units vested		22,700,000	23,200,000
TSR RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock units vested		13,400,000	3,700,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock units vested		$ 557,100,000	$ 454,500,000	$ 445,700,000
Maximum | PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting condition period		3 years
Maximum | TSR RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting condition period		3 years
Minimum | PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting condition period		1 year
Minimum | TSR RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting condition period		2 years
2013 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares initially reserved		68,300,000
Number of shares available for issuance		60,000,000
Outstanding shares of common stock percentage		5.00%
Stock options, restricted stock units and performance restricted stock units outstanding		38,600,000
Common stock, reserved for future issuance		217,900,000
2007 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding		500,000
Shares issued during the period		0
2016 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares initially reserved		6,800,000
Shares issued during the period		0
2013 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance	11,300,000
Outstanding shares of common stock percentage	1.00%
Company's common stock at a discount through payroll deductions	15.00%
Lower fair market value of common stock on the first trading day	85.00%

Common Stock and Stockholders_4

Common Stock and Stockholders' Equity - Summary of Restricted Stock Activity (Details) - Restricted Common Stock shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning of period (in shares) | shares	1,428
Granted (in shares) | shares	1,677
Vested (in shares) | shares	(1,107)
End of period (in shares) | shares	1,998
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning of period (in dollars per share) | $ / shares	$ 24.26
Granted (in dollars per share) | $ / shares	32.90
Vested (in dollars per share) | $ / shares	20.66
End of period (in dollars per share) | $ / shares	$ 34

Common Stock and Stockholders_5

Common Stock and Stockholders' Equity - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Options Outstanding - Number of Shares
Outstanding at beginning of period (in shares)	3,227
Options granted and assumed in connection with acquisitions (in shares)	128
Options exercised (in shares)	(1,882)
Options canceled (in shares)	(37)
Outstanding at end of period (in shares)	1,436	3,227
Exercisable at end of period (in shares)	1,415
Options Outstanding - Weighted-Average Exercise Price Per Share
Outstanding at beginning of period (dollars par share)	$ 9.84
Options granted and assumed in connection with acquisitions (dollars par share)	7.08
Options exercised (dollars par share)	2.89
Options canceled (dollars par share)	0.91
Outstanding at end of period (dollars par share)	18.97	$ 9.84
Exercisable at end of period (dollars par share)	$ 18.87
Options Outstanding - Weighted-Average Remaining Contractual Life
Outstanding (in years)	3 years 4 months 20 days	2 years 7 months 24 days
Exercisable at end of period (in years)	3 years 3 months 25 days
Options Outstanding - Aggregate Intrinsic Value
Outstanding	$ 50,534	$ 74,630
Exercisable at end of period	$ 49,932

Common Stock and Stockholders_6

Common Stock and Stockholders' Equity - Summary of PRSUs Activity (Details) - PRSUs - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning of period (in shares)	646,000
Granted (100% target level) (in shares)	729,000
Vested (in shares)	(646,000)
End of period (in shares)	729,000	646,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning of period (in dollars per share)	$ 31.52
Granted (100% target level) (in dollars per share)	27.77
Vested (in dollars per share)	31.52
End of period (in dollars per share)	$ 27.77	$ 31.52
Shares granted, percentage of target level		100.00%
Shares vested, percentage of target level	100.00%
Performance Period 2019-2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
End of period (in shares)	729,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Award vesting rights, percentage	50.00%
Tranche 2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
End of period (in shares)	365,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Vesting condition period	3 years

Common Stock and Stockholders_7

Common Stock and Stockholders' Equity - Summary of TSR RSUs Activity (Details) - TSR RSUs - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning of period (in dollars per share)	$ 41.15
Granted (100% target level) (in dollars per share)	31.16
Additional earned performance shares related to 2019 grants (in dollars per share)	54.97
Vested (in dollars per share)	54.97
End of period (in dollars per share)	$ 30.90	$ 41.15
Shares granted, percentage of target level		100.00%
Shares vested, percentage of target level	116.00%
Performance Period 2019-2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
End of period (in shares)	430
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested and outstanding (in shares)	430
Award vesting rights, percentage	52.00%
Performance Period 2019-2020 and 2020-2022
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning of period (in shares)	759
Granted (100% target level) (in shares)	487
Additional earned performance shares related to 2019 grants (in shares)	52
Vested (in shares)	(381)
End of period (in shares)	917	759
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested and outstanding (in shares)	917	759
Forecast | Performance Period 2019-2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested and outstanding (in shares)			224

Common Stock and Stockholders_8

Common Stock and Stockholders' Equity - Summary of RSU Activity (Details) - RSUs shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning of period (in shares) | shares	31,731
Granted (in shares) | shares	23,795
Vested (in shares) | shares	(15,768)
Canceled (in shares) | shares	(3,147)
End of period (in shares) | shares	36,611
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning of period (in dollars per share) | $ / shares	$ 29.74
Granted (in dollars per share) | $ / shares	32.24
Vested (in dollars per share) | $ / shares	27.41
Canceled (in dollars per share) | $ / shares	30.78
End of period (in dollars per share) | $ / shares	$ 32.28

Common Stock and Stockholders_9

Common Stock and Stockholders' Equity - Compensation Expense Allocated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 474,932	$ 378,025	$ 326,228
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	32,020	22,797	17,289
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	281,092	209,063	183,799
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	98,748	85,739	71,305
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 63,072	$ 60,426	$ 53,835

Income Taxes - Summary of Domes

Income Taxes - Summary of Domestic and Foreign Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (72,850)	$ 317,135	$ 193,500
Foreign	21,911	73,004	230,044
Income (loss) before income taxes	$ (50,939)	$ 390,139	$ 423,544

Income Taxes - Components of Pr

Income Taxes - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ (199)	$ 563	$ (1,661)
State	677	3,375	4,083
Foreign	19,813	43,053	17,246
Total current provision for income taxes	20,291	46,991	19,668
Deferred:
Federal	(35,651)	2,023	(711,084)
State	(2,248)	2,050	(49,047)
Foreign	1,102,295	(1,126,584)	(41,589)
Total deferred provision (benefit) for income taxes	1,064,396	(1,122,511)	(801,720)
Provision (benefit) for income taxes	$ 1,084,687	$ (1,075,520)	$ (782,052)

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Statutory Federal Income Tax Rate to Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax at federal statutory rate	$ (10,697)	$ 81,929	$ 88,944
State taxes, net of federal benefit	(1,246)	4,286	(35,521)
Stock-based compensation	(27,127)	(19,005)	(27,228)
Research and development credits	(40,707)	(33,044)	(23,490)
Valuation allowance	1,104,732	(724)	(758,707)
Nondeductible other expenses	7,438	12,266	682
Nondeductible Federal Trade Commission settlement accrual	31,500	0	0
Deferred tax asset on intra-entity transfer of intangible assets	0	(1,203,381)	0
Foreign rate differential	22,078	79,186	(27,002)
Other	(1,284)	2,967	270
Provision (benefit) for income taxes	$ 1,084,687	$ (1,075,520)	$ (782,052)

Income Taxes - Schedule of Tax

Income Taxes - Schedule of Tax Effects of Temporary Differences and Related Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 421,411	$ 390,005
Tax credits	485,106	425,011
Fixed assets and intangible assets	1,280,597	1,214,070
Operating lease liability	230,837	170,817
Other	82,596	90,115
Total deferred tax assets	2,500,547	2,290,018
Valuation allowance	(1,457,137)	(223,775)
Total deferred tax assets, net of valuation allowance	1,043,410	2,066,243
Deferred tax liabilities:
Operating lease right-of-use asset	(215,663)	(157,845)
Other	(32,451)	(1,138)
Total deferred tax liabilities	(248,114)	(158,983)
Net deferred tax assets	$ 795,296	$ 1,907,260

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Dec. 31, 2017
Income Tax [Line Items]
Deferred tax asset valuation allowance	$ 1,457,137	$ 1,457,137	$ 223,775
Deferred tax assets, net	796,326	796,326	1,908,086
Deferred income taxes		1,064,396	(1,122,511)	$ (801,720)
Deferred tax assets establishment related to intra-entity transfers of intangible assets		0	1,206,880	0
Release of valuation allowance		1,101,374	0	0
Unrecognized tax benefits	354,598	354,598	419,858	$ 332,314		$ 259,781
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	275,600
Unrecognized tax benefits, period increase (decrease)	96,900
Unrecognized tax benefits, income tax penalties and interest accrued	7,200	7,200	5,300
California Enterprise Zone
Income Tax [Line Items]
Credit carryforwards amount	19,100	$ 19,100
Credit carryforward, expiration year		2023
Federal
Income Tax [Line Items]
Deferred tax asset valuation allowance	15,200	$ 15,200	13,900
Net operating loss carryforwards	2,190,000	$ 2,190,000
Operating loss carryforwards, expiration year		2034
Credit carryforward, expiration start year		2027
Federal | Research
Income Tax [Line Items]
Credit carryforwards amount	398,400	$ 398,400
State
Income Tax [Line Items]
Deferred tax asset valuation allowance	229,200	229,200	209,900
Net operating loss carryforwards	1,280,000	$ 1,280,000
Operating loss carryforwards, expiration year		2024
State | Research
Income Tax [Line Items]
Credit carryforwards amount	297,100	$ 297,100
Brazilian Operations
Income Tax [Line Items]
Deferred tax asset valuation allowance					$ 1,100,000
Release of valuation allowance		(1,210,000)	$ 845,100
Net operating loss carryforwards	$ 59,200	$ 59,200

Income Taxes - Schedule of Re_2

Income Taxes - Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits at the beginning of the year	$ 419,858	$ 332,314	$ 259,781
Increases related to prior year tax positions	5,943	54,743	20,000
Decreases related to prior year tax positions	(99,540)	(2,537)	(13,174)
Increases related to current year tax positions	28,337	35,338	66,249
Statute of limitations expirations	0	0	(542)
Gross unrecognized tax benefits at the end of the year	$ 354,598	$ 419,858	$ 332,314

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits Recorded in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Uncertainties [Abstract]
Total unrecognized tax benefits balance	$ 354,598	$ 419,858	$ 332,314	$ 259,781
Amounts netted against related deferred tax assets	(331,339)	(401,818)
Unrecognized tax benefits recorded on consolidated balance sheets	$ 23,259	$ 18,040

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	Jan. 31, 2021	Jan. 15, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020
Subsequent Event
Other Commitments [Line Items]
Insurance settlements receivable	$ 38,000,000
Stock repurchase program, authorized amount		$ 2,000,000,000
Federal Trade Commissions [Member] | Unfavorable Regulatory Action [Member]
Other Commitments [Line Items]
Loss contingency accrual					$ 150,000,000
Federal Trade Commissions [Member] | Minimum | Unfavorable Regulatory Action [Member]
Other Commitments [Line Items]
Loss contingency, estimate of possible loss					$ 150,000,000
Federal Trade Commissions [Member] | Maximum | Unfavorable Regulatory Action [Member]
Other Commitments [Line Items]
Loss contingency, estimate of possible loss				$ 250,000,000
Revolving Credit Facility
Other Commitments [Line Items]
Unsecured revolving credit facility			$ 500,000,000
Line of credit facility amount			$ 0

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Commitments to Settle Contractual Obligations in Cash (Details) $ in Thousands	Dec. 31, 2020USD ($)
Other Commitments [Line Items]
Total	$ 7,371,087
Payments Due by Next Year	1,444,292
Payments Due by Year 1-3 years	1,017,711
Payments Due by Year 3-5 years	3,300,411
Payments Due by Year More than 5 years	1,608,673
Sublease income	(10,329)
2021 Notes
Other Commitments [Line Items]
Total	963,540
Payments Due by Next Year	963,540
Payments Due by Year 1-3 years	0
Payments Due by Year 3-5 years	0
Payments Due by Year More than 5 years	0
2024 Notes
Other Commitments [Line Items]
Total	1,160,039
Payments Due by Next Year	2,867
Payments Due by Year 1-3 years	5,734
Payments Due by Year 3-5 years	1,151,438
Payments Due by Year More than 5 years	0
2025 Notes
Other Commitments [Line Items]
Total	1,016,825
Payments Due by Next Year	3,740
Payments Due by Year 1-3 years	7,480
Payments Due by Year 3-5 years	1,005,605
Payments Due by Year More than 5 years	0
2027 Notes
Other Commitments [Line Items]
Total	889,819
Payments Due by Next Year	27,106
Payments Due by Year 1-3 years	54,213
Payments Due by Year 3-5 years	54,287
Payments Due by Year More than 5 years	754,213
Operating Lease Obligations
Other Commitments [Line Items]
Total	1,671,283
Payments Due by Next Year	218,869
Payments Due by Year 1-3 years	430,418
Payments Due by Year 3-5 years	354,254
Payments Due by Year More than 5 years	667,742
Finance Lease Obligations
Other Commitments [Line Items]
Total	569
Payments Due by Next Year	569
Payments Due by Year 1-3 years	0
Payments Due by Year 3-5 years	0
Payments Due by Year More than 5 years	0
Other Contractual Commitments
Other Commitments [Line Items]
Total	1,669,012
Payments Due by Next Year	227,601
Payments Due by Year 1-3 years	519,866
Payments Due by Year 3-5 years	734,827
Payments Due by Year More than 5 years	$ 186,718

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transactions [Abstract]
Revenue recognized under contractual obligations from customers	$ 22	$ 22	$ 25.9
Revenue receivable under contractual obligations from customers	$ 5	$ 4.2

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Employer discretionary contribution amount	$ 11	$ 8.8	$ 6.3

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Deferred Tax Assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 223,775	$ 210,862	$ 1,021,326
Charged to Expenses	1,124,132	12,913	(817,529)
Charged/Credited to Other Accounts	109,230	0	7,065
Balance at End of Year	1,457,137	223,775	210,862
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	2,401	3,559	5,430
Additions (Reductions)	17,190	3,083	1,610
Write-off/ Adjustments	(2,645)	(4,241)	(3,481)
Balance at End of Year	$ 16,946	$ 2,401	$ 3,559

Uncategorized Items - twtr-2020

Label	Element	Value
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	$ 2,287,000
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	1,862,000
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	1,698,000
Restricted Cash and Cash Equivalents, Noncurrent	us-gaap_RestrictedCashAndCashEquivalentsNoncurrent	20,560,000
Restricted Cash and Cash Equivalents, Noncurrent	us-gaap_RestrictedCashAndCashEquivalentsNoncurrent	26,722,000
Restricted Cash and Cash Equivalents, Noncurrent	us-gaap_RestrictedCashAndCashEquivalentsNoncurrent	$ 25,733,000