Twitter (TWTR) 10-K 27 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 17, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Trading Symbol	TWTR
Entity Registrant Name	TWITTER, INC.
Entity Central Index Key	1,418,091
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		726,894,203
Entity Public Float			$ 10,883,506,044

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 988,598	$ 911,471
Short-term investments	2,785,981	2,583,877
Accounts receivable, net of allowance for doubtful accounts of $7,216 and $8,121 as of December 31, 2016 and December 31, 2015, respectively	650,650	638,694
Prepaid expenses and other current assets	226,967	247,750
Total current assets	4,652,196	4,381,792
Property and equipment, net	783,901	735,299
Intangible assets, net	95,334	141,015
Goodwill	1,185,315	1,122,728
Other assets	153,619	61,605
Total assets	6,870,365	6,442,439
Current liabilities:
Accounts payable	122,236	134,081
Accrued and other current liabilities	380,937	283,792
Capital leases, short-term	80,848	88,166
Total current liabilities	584,021	506,039
Convertible notes	1,538,967	1,455,095
Capital leases, long-term	66,837	59,695
Deferred and other long-term tax liabilities, net	7,556	2,978
Other long-term liabilities	68,049	50,585
Total liabilities	2,265,430	2,074,392
Commitments and contingencies (Note 14)
Stockholders' equity:
Preferred stock, $0.000005 par value-- 200,000 shares authorized; none issued and outstanding
Common stock, $0.000005 par value-- 5,000,000 shares authorized; 721,572 and 694,132 shares issued and outstanding as of December 31, 2016 and December 31, 2015, respectively	4	3
Additional paid-in capital	7,224,534	6,507,087
Accumulated other comprehensive loss	(69,253)	(45,566)
Accumulated deficit	(2,550,350)	(2,093,477)
Total stockholders' equity	4,604,935	4,368,047
Total liabilities and stockholders' equity	$ 6,870,365	$ 6,442,439

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 7,216	$ 8,121
Preferred stock, par value	$ 0.000005	$ 0.000005
Preferred stock, shares authorized	200,000,000	200,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.000005	$ 0.000005
Common stock, shares authorized	5,000,000,000	5,000,000,000
Common stock, shares issued	721,572,000	694,132,000
Common stock, shares outstanding	721,572,000	694,132,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenue	$ 2,529,619	$ 2,218,032	$ 1,403,002
Costs and expenses
Cost of revenue	932,240	729,256	446,309
Research and development	713,482	806,648	691,543
Sales and marketing	957,829	871,491	614,110
General and administrative	293,276	260,673	189,906
Total costs and expenses	2,896,827	2,668,068	1,941,868
Loss from operations	(367,208)	(450,036)	(538,866)
Interest expense	(99,968)	(98,178)	(35,918)
Other income (expense), net	26,342	14,909	(3,567)
Loss before income taxes	(440,834)	(533,305)	(578,351)
Provision (benefit) for income taxes	16,039	(12,274)	(531)
Net loss	$ (456,873)	$ (521,031)	$ (577,820)
Net loss per share attributable to common stockholders:
Basic	$ (0.65)	$ (0.79)	$ (0.96)
Diluted	$ (0.65)	$ (0.79)	$ (0.96)
Weighted-average shares used to compute net loss per share attributable to common stockholders:
Basic	702,135	662,424	604,990
Diluted	702,135	662,424	604,990

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (456,873)	$ (521,031)	$ (577,820)
Other comprehensive income (loss):
Change in unrealized gain (loss) on investments in available-for-sale securities, net of tax	1,685	(3,019)	(877)
Change in foreign currency translation adjustment	(25,372)	(32,523)	(8,824)
Net change in accumulated other comprehensive loss	(23,687)	(35,542)	(9,701)
Comprehensive loss	$ (480,560)	$ (556,573)	$ (587,521)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance, beginning of period at Dec. 31, 2013		$ 3	$ 3,944,952	$ (323)	$ (994,626)
Balance, beginning of period, shares at Dec. 31, 2013		569,922
Issuance of common stock in connection with RSU vesting, shares		42,748
Issuance of common stock in connection with acquisitions			147,958
Issuance of common stock in connection with acquisitions, shares		3,326
Issuance of restricted stock in connection with acquisitions accounted for as stock-based compensation, shares		2,337
Exercise of stock options			28,881
Exercise of stock options, shares		22,447
Issuance of common stock upon purchases under employee stock purchase plan			42,402
Issuance of common stock upon purchases under employee stock purchase plan, shares		1,887
Shares withheld related to net share settlement of equity awards			(17,053)
Shares withheld related to net share settlement of equity awards, shares		(307)
Stock-based compensation			672,371
Equity component of the convertible note issuance, net			505,982
Purchase of convertible note hedge			(407,169)
Issuance of warrants			289,272
Other activities			1,274
Other activities, shares		25
Other comprehensive income (loss)	$ (9,701)			(9,701)
Net loss	(577,820)				(577,820)
Balance, end of period at Dec. 31, 2014	$ 3,626,403	$ 3	5,208,870	(10,024)	(1,572,446)
Balance, end of period, shares at Dec. 31, 2014	642,385	642,385
Issuance of common stock in connection with RSU vesting, shares		24,002
Issuance of common stock in connection with acquisitions			516,538
Issuance of common stock in connection with acquisitions, shares		13,613
Issuance of restricted stock in connection with acquisitions accounted for as stock-based compensation, shares		2,533
Exercise of stock options			17,914
Exercise of stock options, shares		10,992
Issuance of common stock upon purchases under employee stock purchase plan			39,295
Issuance of common stock upon purchases under employee stock purchase plan, shares	1,500	1,525
Shares withheld related to net share settlement of equity awards			(11,101)
Shares withheld related to net share settlement of equity awards, shares		(281)
Stock-based compensation			729,193
Other activities			6,378
Other activities, shares		(637)
Other comprehensive income (loss)	$ (35,542)			(35,542)
Net loss	(521,031)				(521,031)
Balance, end of period at Dec. 31, 2015	$ 4,368,047	$ 3	6,507,087	(45,566)	(2,093,477)
Balance, end of period, shares at Dec. 31, 2015	694,132	694,132
Issuance of common stock in connection with RSU vesting		$ 1
Issuance of common stock in connection with RSU vesting, shares		26,909
Issuance of common stock in connection with acquisitions			735
Issuance of common stock in connection with acquisitions, shares		41
Issuance of restricted stock in connection with acquisitions accounted for as stock-based compensation, shares		3,364
Exercise of stock options			7,714
Exercise of stock options, shares	2,864	2,864
Issuance of common stock upon purchases under employee stock purchase plan			24,431
Issuance of common stock upon purchases under employee stock purchase plan, shares	2,000	2,039
Shares withheld related to net share settlement of equity awards			(15,598)
Shares withheld related to net share settlement of equity awards, shares		(878)
Cancellation of shares contributed by the CEO		(6,814)
Stock-based compensation			695,525
Other activities			4,640
Other activities, shares		(85)
Other comprehensive income (loss)	$ (23,687)			(23,687)
Net loss	(456,873)				(456,873)
Balance, end of period at Dec. 31, 2016	$ 4,604,935	$ 4	$ 7,224,534	$ (69,253)	$ (2,550,350)
Balance, end of period, shares at Dec. 31, 2016	721,572	721,572

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net loss	$ (456,873)	$ (521,031)	$ (577,820)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	402,172	312,823	208,165
Stock-based compensation expense	615,233	682,118	631,597
Amortization of discount on convertible notes	74,660	69,185	18,823
Changes in bad debt provision	3,958	5,765	4,632
Deferred income tax	(4,775)	(28,125)	(9,609)
Non-cash restructuring	25,934	(3,194)
Other adjustments	20,150	1,438	7,983
Changes in assets and liabilities, net of assets acquired and liabilities assumed from acquisitions:
Accounts receivable	(22,969)	(216,585)	(177,583)
Prepaid expenses and other assets	7,101	(50,170)	(165,395)
Accounts payable	(7,112)	76,355	18,059
Accrued and other liabilities	105,576	54,487	122,944
Net cash provided by operating activities	763,055	383,066	81,796
Cash flows from investing activities
Purchases of property and equipment	(218,657)	(347,280)	(201,630)
Purchases of marketable securities	(2,908,611)	(3,683,488)	(2,937,033)
Proceeds from maturities of marketable securities	2,518,631	2,821,745	2,029,518
Proceeds from sales of marketable securities	183,154	383,413	188,092
Changes in restricted cash	(4,760)	(3,549)	(11,042)
Purchases of investments in privately-held companies	(81,502)	(10,500)
Business combinations, net of cash acquired	(85,082)	(51,644)	(163,477)
Other investing activities	(1,181)	(11,118)	(1,700)
Net cash used in investing activities	(598,008)	(902,421)	(1,097,272)
Cash flows from financing activities
Proceeds from issuance of convertible notes			1,889,000
Convertible notes initial issuance discount			(28,810)
Purchases of convertible note hedges			(407,169)
Proceeds from issuance of warrants			289,272
Taxes paid related to net share settlement of equity awards	(15,598)	(11,101)	(17,053)
Repayments of capital lease obligations	(100,558)	(117,535)	(103,135)
Proceeds from exercise of stock options	7,540	17,361	28,658
Proceeds from issuances of common stock under employee stock purchase plan	24,431	39,295	42,402
Other financing activities	210	8,982	(1,443)
Net cash provided by (used in) financing activities	(83,975)	(62,998)	1,691,722
Net increase (decrease) in cash and cash equivalents	81,072	(582,353)	676,246
Foreign exchange effect on cash and cash equivalents	(3,945)	(16,900)	(6,532)
Cash and cash equivalents at beginning of period	911,471	1,510,724	841,010
Cash and cash equivalents at end of period	988,598	911,471	1,510,724
Supplemental cash flow data
Interest paid in cash	12,953	15,985	10,000
Taxes paid in cash	14,532	8,229	14,895
Supplemental disclosures of non-cash investing and financing activities
Common stock issued in connection with acquisitions	1,341	516,538	147,958
Equipment purchases under capital leases	100,281	31,215	140,685
Changes in accrued property and equipment purchases	$ 5,738	$ 3,902	$ 6,562

The Company

The Company	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
The Company	Note 1. The Company Twitter, 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 users, advertisers and data partners.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. 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. Certain prior period amounts have been reclassified to conform to the current period presentation. Revenue Recognition The Company generates the substantial majority of its revenue from the sale of advertising services and, to a lesser extent, from entering into data licensing and other arrangements. The Company’s advertising services include three primary products: (i) Promoted Tweets, (ii) Promoted Accounts and (iii) Promoted Trends. Promoted Tweets and Promoted Accounts are pay-for-performance advertising products 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 user engages with a Promoted Tweet or follows a Promoted Account or when a Promoted Trend is displayed. These products may be sold in combination as a multiple element arrangement or separately on a stand-alone basis. The Company also generates advertising revenue by selling to advertisers advertising products which it places 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 it has identified the advertisers’ targeted audience and therefore incurs traffic acquisition costs. In such transactions, the Company remains the primary obligor to its advertisers for the advertising services and products delivered, has pricing latitude, has discretion in the selection of third party publishers and bears credit risk. The Company might not generate advertising revenue in excess of traffic acquisition costs incurred. Therefore, the Company reports advertising revenue generated from these transactions on a gross basis. Fees for these advertising services are recognized in the period when advertising is delivered as evidenced by a user engaging with a Promoted Tweet in a manner satisfying the types of engagement selected by the advertisers, such as Tweet engagements (e.g., retweets, replies and likes), website clicks or conversions, mobile application installs or engagements, obtaining new followers, or video views, following a Promoted Account, through the display of a Promoted Trend on the Company’s platform, or completion of a transaction on an external website. Data licensing revenue is generated based on monthly service fees charged to the data partners over the period in which the Company’s data and data products are made available to them. 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 and matches buyers and sellers. 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. Therefore, the Company reports revenue related to its ad exchange services on a net basis. Revenue is recognized only when (1) persuasive evidence of an arrangement exists; (2) the price is fixed or determinable; (3) the service is performed; and (4) collectability of the related fee is reasonably assured. 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 elements. For arrangements involving multiple deliverables, judgment is required to determine the appropriate accounting, including developing an estimate of the stand-alone selling price of each deliverable. When neither vendor-specific objective evidence nor third-party evidence of selling price exists, the Company uses its best estimate of selling price (BESP) to allocate the arrangement consideration on a relative selling price basis to each deliverable. The objective of BESP is to determine the selling price of each deliverable when it is sold to advertisers on a stand-alone basis. In determining BESPs, the Company takes into consideration various factors, including, but not limited to, prices the Company charges for similar offerings, sales volume, geographies, pricing strategies and market conditions. Multiple deliverable arrangements 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 selling price for these products in order to allocate any potential discount to all advertising products in the arrangement. The estimate of selling price for pay-for-performance products is determined based on the winning bid price; the estimate of selling price for Promoted Trends is based on Promoted Trends sold on a stand-alone basis and/or separately priced in a bundled arrangement by reference to a list price by geography which is approved periodically. The Company believes the use of BESP results in revenue recognition in a manner consistent with the underlying economics of the transaction and allocates the arrangement consideration on a relative selling price basis to each deliverable. Cost of Revenue Cost of revenue includes infrastructure costs, other direct costs including content costs, amortization expense of technology acquired through acquisitions and capitalized labor costs, 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, as well as depreciation of its servers and networking equipment, and personnel-related costs, including salaries, benefits and stock-based compensation, for its operations teams. 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 and from the Company’s organically-built advertising network, Twitter Audience Platform. 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. The Company recognizes the compensation expense only for those awards expected to meet the performance and service vesting condition on a straight-line basis over the requisite service period which is generally one year for performance vesting condition awards and four years for service vesting condition awards. 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. Calculating the fair value using the Black-Scholes model requires various judgmental assumptions including the expected term and stock price volatility. The Company estimates the expected term of stock options granted based on the simplified method. The Company estimates the expected volatility of its common stock on the dates of grant based on a combination of the Company’s historical stock price volatility and implied volatility in the Company’s traded options when such information is available. When the Company’s historical and implied volatility data are not available for the related awards’ expected term, an average of volatility rates including the historical volatility of a group of comparable, publicly-traded companies is used. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. Expected dividend yield is zero percent as the Company has not paid and does not anticipate paying dividends on its common stock. 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 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. Stock-based compensation expense is recorded net of estimated forfeitures. Through 2016, the Company estimated the forfeiture rate based on historical forfeitures of stock-based awards and adjusted the rate to reflect changes in facts and circumstances, if any. Acquisitions The Company accounts for acquisitions of entities that include inputs and processes and have the ability to create outputs as business combinations. The purchase price of the acquisition is allocated 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 and assesses the accounting for these investments under the equity or cost method. 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 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 determines the fair value by reviewing equity valuation reports, current financial results and long-term plans of the private companies. Restructuring and Other Charges The Company records charges associated with management-approved restructuring plans to reduce headcount and for leases. Restructuring costs are recognized when the related liability is incurred and measured at fair value. The Company accrues a liability for employee terminations when all of the following conditions have been met: management, having the authority to approve the action, commits to a plan of termination; the plan identifies the number of employees to be terminated, their job classifications and their locations, and the expected completion date; the plan establishes the terms of the benefit arrangement in sufficient detail to enable employees to determine the type and amount of benefits they will receive if they are involuntarily terminated; and actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. The Company accrues for costs to terminate an operating lease or other contract when it terminates the contract in accordance with the contract terms. A liability for costs that will continue to be incurred under a contract for the remaining term without economic benefits to the Company is recognized and measured when the entity meets the cease-use date. In recording liabilities for cease-use facilities, the Company makes various assumptions, including the time period over which the facilities are expected to be vacant, expected sublease terms and expected sublease rates. The estimates involve a number of risks and uncertainties, some of which are beyond the Company’s control, including future real estate market conditions and the Company’s ability to successfully enter into sublease agreements with terms as favorable as those assumed when arriving at the estimates. The Company regularly evaluates a number of factors to determine the appropriateness and reasonableness of the restructuring and lease loss accruals including the various assumptions noted above. If actual results differed significantly from its estimates, the Company may be required to adjust the restructuring and lease loss accruals in the future. Operating and Capital Leases The Company leases office space and data center facilities under operating leases. Certain lease agreements contain free or escalating rent payment provisions. The Company recognizes rent expense under such leases on a straight-line basis over the term of the lease. Lease renewal periods are considered on a lease-by-lease basis in determining the lease term. The Company also has entered into server and networking equipment lease arrangements with original lease terms ranging from three to four years. The Company’s server and networking equipment leases typically are accounted for as capital leases as they meet one or more of the four capital lease classification criteria. Assets acquired under capital leases are amortized over their estimated useful life. As of December 31, 2016 and 2015, the Company had capital lease obligations included in short-term and long-term capital lease obligations in the consolidated balance sheets of $147.7 million and $147.9 million, respectively. In the years ended December 31, 2016, 2015 and 2014, the Company recorded approximately $5.5 million, $8.8 million and $10.2 million, respectively, of interest expense in relation to these capital lease arrangements. 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, 2016 and 2015, the Company has recorded restricted cash balances of $9.4 million and $3.0 million, respectively, within prepaid expenses and other current assets and $29.6 million and $31.1 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, and reports the unrealized gains and losses, net of taxes, as a component of stockholders’ equity, except for unrealized losses determined to be other-than-temporary which are recorded as other income (expense), net. 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 $24.3 million, $9.1 million, and $1.9 million during the years ended December 31, 2016, 2015 and 2014, respectively. These balances are recorded in other income (expense), net in the accompanying consolidated statements of operations. The Company evaluates the investments periodically for possible other-than-temporary impairment. A decline in fair value below the amortized costs of debt securities is considered an other-than-temporary impairment if the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security before recovery of the entire amortized cost basis. In those instances, an impairment charge equal to the difference between the fair value and the amortized cost basis is recognized in earnings. Regardless of the Company’s intent or requirement to sell a debt security, impairment is considered other-than-temporary if the Company does not expect to recover the entire amortized cost basis. 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 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, 2016 and 2015, no single customer accounted for more than 10% of the Company’s net accounts receivable balance. No single customer accounted for more than 10% of the Company’s revenue in the years ended December 31, 2016, 2015 and 2014. The Company’s note hedge transactions, entered into in connection with the Notes, as defined and further described in Note 4— Fair Value Measurements 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, and the customer’s current financial condition. 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 to five years Computer software One to four years Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term 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 is capitalized for assets that are constructed for the Company’s own internal use, this includes internally developed software and property and equipment, for the period of time to get them ready for its intended use. During the years ended December 31, 2016 and 2015, the Company capitalized $4.3 million and $5.0 million of interest expense, respectively. Capitalized interest was not material in 2014. 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, the second step of the test is performed by comparing the carrying value of the goodwill in the reporting unit to its implied fair value. An impairment charge is recognized for the excess of the carrying value of goodwill over its implied fair value. The Company conducted its annual goodwill impairment test during the fourth quarter of 2016 and determined that goodwill was not impaired. As such, no impairment charge was recorded in any of the periods presented in the accompanying consolidated financial statements. Intangible Assets Intangible 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. There has been no impairment charges recorded in any of the periods presented in the accompanying consolidated financial statements. 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 The Company capitalizes certain costs incurred in developing software programs or websites for internal use. In the years ended December 31, 2016, 2015 and 2014, the Company capitalized costs totaling approximately $139.0 million, $92.8 million and $79.5 million, respectively. The estimated useful life of costs capitalized is evaluated for each specific project and is one to four years. In the years ended December 31, 2016, 2015 and 2014, the amortization of capitalized costs included in cost of revenue totaled approximately $74.6 million, $37.8 million and $15.2 million, respectively. Income Taxes The Company accounts for its income taxes using the asset and liability method whereby deferred tax assets and liabilities are determined based on temporary differences between the bases used for financial reporting and income tax reporting purposes, as well as for operating loss and tax credit carryforwards. Deferred income taxes are provided based on the enacted tax rates expected to be in effect at the time such temporary differences are expected to reverse. A valuation allowance is provided for deferred tax assets if it is more-likely-than-not that the Company will not realize those tax assets through future operations. The Company evaluates and accounts for uncertain tax positions using a two-step approach. Recognition (step one) occurs when the Company concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustainable upon examination. Measurement (step two) determines the amount of benefit that is greater than 50% likely to be realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. De-recognition of a tax position that was previously recognized would occur when the Company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. Although the Company believes that it has adequately reserved for uncertain tax positions, the Company can provide no assurance that the final tax outcome of these matters will not be materially different. The Company makes adjustments to these reserves when facts and circumstances change, such as the closing of a tax audit, the lapsing of a statute, or the refinement of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on the Company’s financial position and results of operations. 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 costs are expensed when incurred and are included in sales and marketing expense in the accompanying consolidated statements of operations. Advertising expense totaled $114.3 million, $119.7 million and $46.6 million for the years ended December 31, 2016, 2015 and 2014 respectively. Comprehensive Loss Comprehensive loss consists of two components, net 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 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 Recently adopted accounting pronouncement In June 2014, the Financial Accounting Standards Board (“FASB”) issued a new accounting standard update on stock-based compensation when the terms of an award provide that a performance target could be achieved after the requisite service period. The new guidance requires that a performance target that affects vesting, and that could be achieved after the requisite service period, be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. This update further clarifies that compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the periods for which the requisite service has already been rendered. The Company adopted this guidance prospectively during the year ended December 31, 2016, and the adoption had no impact to the Company’s financial statements. In February 2015, the FASB issued a new accounting standard update on consolidation analysis. The new guidance amends the current consolidation guidance with respect to the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. This guidance became effective for reporting periods beginning after December 15, 2015. The Company adopted this guidance retrospectively during the year ended December 31, 2016, and the adoption had no impact on the Company’s financial statements. In April 2015, the FASB issued a new accounting standard update on the presentation of debt issuance costs. The new guidance requires the debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. The Company adopted this guidance retrospectively during the year ended December 31, 2016 and the adoption had an immaterial impact on the Company’s financial statements. In September 2015, the FASB issued a new accounting standard update on simplifying the accounting for measurement-period adjustments in business combinations. The new guidance requires that the adjustments to provisional amounts that are identified during the measurement period be recognized in the reporting period when the adjustments are determined. In addition, the effect on earnings of changes as a result of the change to the provisional amounts is required to be recorded in the same period’s financial statements. The Company adopted this guidance prospectively on January 1, 2016, and the adoption had no impact on the Company’s financial statements. Recently issued accounting pronouncements not yet adopted In May 2014, the FASB issued a new accounting standard update on revenue recognition from contracts with customers. The new guidance will replace all current GAAP guidance on this topic and eliminate industry-specific guidance. According to the new guidance, revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration for which the Company expects to be entitled in exchange for those goods or services. The guidance will be effec

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-term Investments	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Cash, Cash Equivalents and Short-term Investments	Note 3. Cash, Cash Equivalents and Short-term Investments Cash, cash equivalents and short-term investments consist of the following (in thousands): December 31, December 31, 2016 2015 Cash and cash equivalents: Cash $ 253,808 $ 300,363 Money market funds 422,515 141,700 U.S. government and agency securities including treasury bills 12,639 — Corporate notes, commercial paper and certificates of deposit 299,636 469,408 Total cash and cash equivalents $ 988,598 $ 911,471 Short-term investments: U.S. government and agency securities including treasury bills $ 1,183,768 $ 1,156,418 Corporate notes, commercial paper and certificates of deposit 1,602,213 1,427,459 Total short-term investments $ 2,785,981 $ 2,583,877 The following tables summarize unrealized gains and losses related to available-for-sale securities classified as short-term investments on the Company’s consolidated balance sheets as of December 31, 2016 and 2015 (in thousands): December 31, 2016 Gross Gross Gross Aggregated Amortized Unrealized Unrealized Estimated Costs Gains Losses Fair Value U.S. government and agency securities including treasury bills $ 1,185,274 $ 136 $ (1,642 ) $ 1,183,768 Corporate notes, commercial paper and certificates of deposit 1,603,048 114 (949 ) 1,602,213 Total available-for-sale securities classified as short-term investments $ 2,788,322 $ 250 $ (2,591 ) $ 2,785,981 December 31, 2015 Gross Gross Gross Aggregated Amortized Unrealized Unrealized Estimated Costs Gains Losses Fair Value U.S. government and agency securities including treasury bills $ 1,158,479 $ 6 $ (2,067 ) $ 1,156,418 Corporate notes, certificates of deposit and commercial paper 1,429,374 21 (1,936 ) 1,427,459 Total available-for-sale securities classified as short-term investments $ 2,587,853 $ 27 $ (4,003 ) $ 2,583,877 The available-for-sale 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 and their carrying value approximates fair value because of the short maturity period of these instruments. The contractual maturities of securities classified as available-for-sale as of December 31, 2016 were as follows (in thousands): December 31, 2016 Due within one year $ 1,990,083 Due after one year through two years 795,898 Total $ 2,785,981 The gross unrealized loss on securities in a continuous loss position for 12 months or longer was not material as of December 31, 2016 and there were no securities in a continuous loss position for 12 months or longer as of December 31, 2015. Investments are reviewed periodically to identify possible other-than-temporary impairments. No impairment loss has been recorded on the securities included in the tables above as the Company believes that the decrease in fair value of these securities is temporary and expects to recover at least up to the initial cost of investment for these securities.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 4. Fair Value Measurements The 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, 2016 and 2015 based on the three-tier fair value hierarchy (in thousands): December 31, 2016 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 422,515 $ — $ — $ 422,515 Treasury bills 12,639 — — 12,639 Corporate notes — 7,387 — 7,387 Commercial paper — 292,249 — 292,249 Short-term investments: U.S. government securities — 657,502 — 657,502 Agency securities — 526,266 — 526,266 Corporate notes — 689,986 — 689,986 Commercial paper — 311,238 — 311,238 Certificates of deposit — 600,989 — 600,989 Other current assets: Foreign currency contracts — 1,955 — 1,955 Total $ 435,154 $ 3,087,572 $ — $ 3,522,726 Liabilities Other current liabilities: Foreign currency contracts — 500 — 500 Total $ — $ 500 $ — $ 500 December 31, 2015 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 141,700 $ — $ — $ 141,700 Commercial paper — 419,110 — 419,110 Certificates of deposit — 50,298 — 50,298 Short-term investments: Treasury bills 29,953 — — 29,953 U.S. government securities — 537,168 — 537,168 Agency securities — 589,297 — 589,297 Corporate notes — 693,593 — 693,593 Commercial paper — 229,965 — 229,965 Certificates of deposit — 503,901 — 503,901 Other current assets: Foreign currency contracts — 6,804 — 6,804 Total $ 171,653 $ 3,030,136 $ — $ 3,201,789 Liabilities Other current liabilities: Foreign currency contracts — 3,005 — 3,005 Total $ — $ 3,005 $ — $ 3,005 In 2014, the Company issued $935.0 million principal amount of 0.25% convertible senior notes due in 2019 (the “2019 Notes”) and $954.0 million principal amount of 1.00% convertible senior notes due in 2021 (the “2021 Notes” and together with the 2019 Notes, the “Notes”) in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. Refer to Note 9 – Convertible Senior Notes for further details on the Notes. The estimated fair value of the 2019 Notes and 2021 Notes based on a market approach as of December 31, 2016 was approximately $879.0 million and $880.4 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. 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 as other income (expense), net in the consolidated statements of operations. The notional principal of foreign currency contracts outstanding was equivalent to $536.9 million and $522.4 million at December 31, 2016 and 2015, respectively. The fair values of outstanding derivative instruments for the periods presented on a gross basis are as follows (in thousands): December 31, December 31, Balance Sheet Location 2016 2015 Assets Foreign currency contracts not designated as hedging instruments Other current assets $ 1,955 6,804 Liabilities Foreign currency contracts not designated as hedging instruments Other current liabilities 500 3,005 Total fair value of derivative instruments $ 1,455 $ 3,799 The Company recognized $1.6 million and $0.4 million net gains on the foreign currency contracts in the year ended December 31, 2016 and 2015, respectively. The Company did not have any derivative financial instruments in the year ended December 31, 2014.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Property and Equipment, Net	Note 5. Property and Equipment, Net The following table presents the detail of property and equipment, net for the periods presented (in thousands): December 31, December 31, 2016 2015 Property and equipment, net Equipment $ 909,797 $ 720,421 Furniture and leasehold improvements 304,613 297,274 Capitalized software 353,163 211,241 Construction in progress 74,255 85,073 Total 1,641,828 1,314,009 Less: Accumulated depreciation and amortization (857,927 ) (578,710 ) Property and equipment, net $ 783,901 $ 735,299 The gross carrying amount of property and equipment includes $361.1 million and $370.3 million of server and networking equipment acquired under capital leases as of December 31, 2016 and 2015, respectively. The accumulated depreciation of the equipment under capital leases totaled $207.0 million and $226.9 million as of December 31, 2016 and 2015, respectively. Depreciation expense totaled $332.8 million, $257.2 million and $171.6 million for the years ended December 31, 2016, 2015 and 2014, respectively. Included in these amounts were depreciation expense for server and networking equipment acquired under capital leases in the amount of $100.8 million, $118.7 million and $108.7 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Note 6. Goodwill and Intangible Assets The following table presents the goodwill activities for the periods presented (in thousands): Goodwill Balance as of December 31, 2014 $ 622,570 TellApart acquisition 394,989 Other acquisitions 106,198 Foreign currency translation adjustment (1,029 ) Balance as of December 31, 2015 $ 1,122,728 Acquisitions 74,186 Foreign currency translation adjustment (11,599 ) Balance as of December 31, 2016 $ 1,185,315 For each of the periods presented, gross goodwill balance equaled the net balance since no impairment charges have been recorded. Refer to Note 8— Acquisitions The following table presents the detail of intangible assets for the periods presented (in thousands): Gross Carrying Accumulated Net Carrying Value Amortization Value December 31, 2016: Patents and developed technologies $ 122,611 $ (47,160 ) $ 75,451 Publisher and advertiser relationships 53,100 (33,217 ) 19,883 Total $ 175,711 $ (80,377 ) $ 95,334 December 31, 2015: Patents and developed technologies $ 132,444 $ (43,991 ) $ 88,453 Publisher and advertiser relationships 75,300 (23,803 ) 51,497 Assembled workforce 1,960 (1,714 ) 246 Other intangible assets 2,100 (1,281 ) 819 Total $ 211,804 $ (70,789 ) $ 141,015 Patents and developed technologies are amortized over a period of up to eleven years from the respective purchase dates. Publisher and advertiser relationships are amortized over a period ranging from two to five years, and assembled workforce and other intangible assets are amortized over a period of one to four years. Amortization expense associated with intangible assets for the years ended December 31, 2016, 2015 and 2014 was $69.3 million, $54.7 million and $36.6 million, respectively. During the year ended December 31, 2016, $59.5 million in gross carrying value and accumulated amortization related to fully amortized intangible assets was eliminated. Estimated future amortization expense as of December 31, 2016 is as follows (in thousands): Years ending December 31, 2017 $ 43,810 2018 18,855 2019 8,796 2020 6,523 2021 6,126 Thereafter 11,224 Total $ 95,334

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued and Other Current Liabilities	Note 7. 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, 2016 2015 Accrued compensation $ 82,354 $ 90,906 Accrued restructuring 55,942 396 Accrued publisher, content and ad network costs 44,362 23,486 Deferred revenue 33,659 23,674 Accrued tax liabilities 29,558 25,880 Accrued sales and marketing expenses 22,431 27,948 Accrued other 112,631 91,502 Total $ 380,937 $ 283,792

Acquisitions and Other Investme

Acquisitions and Other Investments	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisition And Other Investments	Note 8. Acquisitions and Other Investments 2016 Acquisitions During the year ended December 31, 2016, the Company acquired several companies, each of which was accounted for as a business combination. The total purchase price of $91.4 million (paid in shares of the Company’s common stock having a total fair value of $1.3 million and cash of $90.1 million) for these acquisitions was allocated as follows: $14.4 million to developed technologies, $5.0 million to cash acquired, $0.2 million to net tangible assets acquired based on their estimated fair value on the acquisition date, $2.4 million to deferred tax liability, and the excess $74.2 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. Tax deductible goodwill resulting from certain of these acquisitions was $63.8 million. The remaining goodwill is not tax deductible for U.S. income tax purposes. Developed technologies will be amortized on a straight-line basis over their estimated useful lives of up to 24 months. The results of operations for each of 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 revenue and results of operations, either individually or in the aggregate. 2015 Acquisitions In May 2015, the Company completed its acquisition of TellApart, Inc. (“TellApart”), a privately held marketing technology company with unique retargeting capabilities headquartered in Burlingame, California. The acquisition was expected to bring the power of retargeting to the Company to help advertisers reach their users. Under the terms of the acquisition, the Company agreed to pay $22.6 million in cash and issue approximately 12.2 million shares of its common stock in consideration for all of the issued and outstanding shares of capital stock of TellApart. In addition, the Company agreed to issue an aggregate of 1.2 million shares of the Company’s common stock and 1.3 million stock options as a result of assumed TellApart equity awards held by individuals, who will continue to provide services to the Company. The fair value of the total consideration of $479.1 million (paid in shares of the Company’s common stock having a total fair value of $456.5 million and cash of $22.6 million) for the acquisition of TellApart was allocated to the acquired tangible and intangible assets and assumed liabilities based on their estimated fair values at closing as follows: $21.4 million to developed technology, $43.3 million to advertiser relationships, $2.1 million to trade name, $29.6 million to cash acquired, $19.7 million to account receivables acquired, $2.2 million to other tangible assets acquired, $11.8 million to liabilities assumed, $22.4 million to deferred tax liability recorded, and the excess $395.0 million of the purchase price over the fair value of net assets acquired was recorded as goodwill. This goodwill is primarily attributable to the expected synergies from potential monetization opportunities and from integrating the retargeting technologies into the Company’s mobile platforms, and the value of acquired talent. Goodwill is not deductible for U.S. income tax purposes. Developed technology, advertiser relationships and trade names were amortized over their estimated useful lives of 12 to 72 months. The discounted cash flow method, which calculates the fair value of an asset based on the value of cash flows that the asset is expected to generate in the future, was used to estimate the fair value of the amortizable intangible assets acquired. During the year ended December 31, 2015, the Company acquired other companies, which were accounted for as business combinations. The total purchase price of $118.9 million (paid in shares of the Company’s common stock having a total fair value of $60.1 million and cash of $58.8 million) for these acquisitions was allocated as follows: $12.9 million to developed technologies, $3.2 million to net tangible assets acquired based on their estimated fair value on the acquisition date, $3.4 million to deferred tax liability, and the excess $106.2 million of the purchase price over the fair value of net assets acquired to goodwill. Tax deductible goodwill resulting from certain of these acquisitions was $4.1 million. The remaining goodwill is not tax deductible for U.S. income tax purposes. Developed technologies will be amortized on a straight-line basis over their estimated useful lives of 12 to 60 months. In connection with all of the acquisitions completed during the year ended December 31, 2015, the Company also agreed to pay cash and issue shares of its common stock with a total fair value up to $102.9 million, which is to be paid to certain employees of the acquired entities contingent upon their continued employment with the Company. The Company will recognize compensation expense related to the equity consideration over the requisite service periods of up to 48 months from the respective acquisition dates on a straight-line basis. In addition, the Company will recognize approximately $37.2 million of stock-based compensation expense in relation to assumed stock options over the remaining requisite service periods of up to 45 months from the respective acquisition dates on a straight-line basis, excluding the fair value of the assumed stock options that was allocated and recorded as part of the purchase price for the portion of the service period completed prior to the closing of the applicable acquisition. The results of operations for each of 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 to the consolidated revenue and results of operations, either individually or in aggregate. 2014 Acquisitions In May 2014, the Company completed its acquisition of privately held Gnip, Inc. (“Gnip”), a leading provider of social data and analytics headquartered in Boulder, Colorado. The acquisition was made to allow the Company to further enhance its data analytics capabilities. During the year ended December 31, 2014, the Company acquired other companies, which were accounted for as business combinations. The total purchase price of $188.1 million (paid in shares of the Company’s common stock having a total fair value of $121.2 million and cash of $66.9 million) for these acquisitions was preliminarily allocated as follows: $28.1 million to developed technologies, $1.6 million to customer relationships, $6.5 million to net tangible assets acquired based on their estimated fair value on the acquisition date, $3.2 million to deferred tax liability, and the excess $155.1 million of the purchase price over the fair value of net assets acquired to goodwill. Tax deductible goodwill resulting from certain of these acquisitions was $21.9 million as of December 31, 2014, the remaining amounts are not tax deductible for U.S. income tax purposes. Developed technologies and customer relationships will be amortized on a straight-line basis over their estimated useful lives of 12 to 48 months. In connection with all of the acquisitions completed during the year ended December 31, 2014, the Company also agreed to pay cash and shares of the Company’s common stock with a total fair value up to $97.7 million, which is to be paid to certain employees of the acquired entities contingent upon their continued employment with the Company. In addition, the fair value of assumed stock options determined to be part of post-acquisition stock-based compensation amounted to approximately $16.9 million. The Company recognizes compensation expense in relation to these cash and equity consideration and assumed stock options over the remaining requisite service periods of up to 48 months from the respective acquisition dates on a straight-line basis. The results of operations for each of 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 to the consolidated revenue and results of operations, either individually or in aggregate. Investments in Privately-Held Companies The Company has determined, as of December 31, 2016, 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 accounted for using the cost method which had a carrying value of $90.2 million and $14.2 million as of December 31, 2016 and 2015, respectively. The maximum loss the Company can incur for its investments is their carrying value. These investments in privately-held companies are included within Other Assets on the consolidated balance sheets.

Convertible Notes

Convertible Notes	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Convertible Notes	Note 9. Convertible Notes In September 2014, the Company issued $900.0 million principal amount of 2019 Notes and $900.0 million principal amount of 2021 Notes in a private placement to qualified institutional buyers pursuant to Rule144A under the Securities Act of 1933, as amended. In October 2014, pursuant to the exercise of the overallotment option by the initial purchasers, the Company issued an additional $35.0 million principal amount of 2019 Notes and $54.0 million principal amount of 2021 Notes. The total net proceeds from this offering were approximately $1.86 billion, after deducting $28.3 million of initial purchasers’ discount and $0.5 million debt issuance costs in connection with the 2019 Notes and the 2021 Notes. The Each $1,000 of principal of these Notes will initially be convertible into 12.8793 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $77.64 per share, subject to adjustment upon the occurrence of specified events. Holders of these notes may convert their notes at their option at any time until close of business on the second scheduled trading day immediately preceding the relevant maturity date which is March 15, 2019 for the 2019 Notes and March 15, 2021 for the 2021 Notes. Further, holders of each of these notes may convert their notes at their option prior to the respective dates above, only under the following circumstances: 1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2014 (and only during such calendar quarters), if the last reported sale price of Twitter’s 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 relevant series of 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 related Indenture) per $1,000 principal amount of 2019 notes or 2021 notes, as applicable, for each trading day of the 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 notes of the relevant series on each such trading day; or 3) upon the occurrence of certain specified Upon conversion of the 2019 Notes and 2021 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 described herein) calculated on a proportionate basis for each trading day in a 30 trading day observation period. If a fundamental change (as defined in the relevant indenture governing the applicable series of Notes) occurs prior to the maturity date, holders of the 2019 Notes and 2021 Notes 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 the notes, plus any accrued and unpaid interest to, but excluding, the repurchase date. In addition, if specific corporate events occur prior to the applicable maturity date, the Company will be required to increase the conversion rate for holders who elect to convert their notes in certain circumstances. In accordance with accounting guidance on embedded conversion features, the Company valued and bifurcated the conversion option associated with the 2019 Notes and 2021 Notes from the respective host debt instrument, which is referred to as debt discount, and initially recorded the conversion option of $222.8 million for the 2019 Notes and $283.3 million for the 2021 Notes in stockholders’ equity. The resulting debt discounts on the 2019 Notes and 2021 Notes are being amortized to interest expense at an effective interest rate of 5.75% and 6.25%, respectively, over the contractual terms of the notes. The Company allocated $0.1 million of debt issuance costs to the equity component, and the remaining debt issuance costs of $0.4 million are being amortized to interest expense. During the years ended December 31, 2016, 2015 and 2014, the Company recognized $79.0 million, $74.2 million and $18.8 million, respectively, of interest expense related to the amortization of the debt discount prior to capitalization of interest. As of December 31, 2016, the net carrying value, net of the initial purchasers’ discount and debt discount, of 2019 Notes and 2021 Notes was $798.6 million and $740.3 million, respectively. The Notes consisted of the following (in thousands): December 31, 2016 December 31, 2015 2019 Notes 2021 Notes 2019 Notes 2021 Notes Principal amounts: Principal $ 935,000 $ 954,000 $ 935,000 $ 954,000 Unamortized initial purchasers' discount and debt discount (1) (136,376 ) (213,657 ) (181,994 ) (251,911 ) Net carrying amount $ 798,624 $ 740,343 $ 753,006 $ 702,089 Carrying amount of the equity component (2) $ 222,826 $ 283,283 $ 222,826 $ 283,283 (1) (2) As of December 31, 2016, the remaining life of the 2019 Notes and 2021 Notes is approximately 32 months and 56 months, respectively. Concurrently with the offering of these Notes in September and October 2014, 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 24.3 million shares of its common stock at a price of approximately $77.64 per share. The total cost of the convertible note hedge transactions was $407.2 million. 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 24.3 million shares of the Company’s common stock at a price of $105.28. The Company received $289.3 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of these notes and to effectively increase the overall conversion price from $77.64 to $105.28 per share. 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 2014.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	Note 10. Net Loss per Share The Company computes net loss per share of common stock in conformity with the two-class method required for participating securities. The Company considers the shares issued upon the early exercise of stock options subject to repurchase to be participating securities, because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. Basic net loss per share is computed by dividing total net loss attributable to common stockholders by the weighted-average common shares outstanding. 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 loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding including potential dilutive common stock instruments. In the years ended December 31, 2016, 2015 and 2014, 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, conversion feature of the 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 loss per share for periods presented (in thousands, except per share data). Year Ended December 31, 2016 2015 2014 Net loss $ (456,873 ) $ (521,031 ) $ (577,820 ) Basic shares: Weighted-average common shares outstanding 708,010 670,132 613,944 Weighted-average restricted stock subject to repurchase (5,875 ) (7,708 ) (8,954 ) Weighted-average shares used to compute basic net loss per share 702,135 662,424 604,990 Diluted shares: Weighted-average shares used to compute diluted net loss per share 702,135 662,424 604,990 Net loss per share attributable to common stockholders: Basic $ (0.65 ) $ (0.79 ) $ (0.96 ) Diluted $ (0.65 ) $ (0.79 ) $ (0.96 ) The following number of potential common shares at the end of each period were excluded from the calculation of diluted net 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, 2016 2015 2014 RSUs 48,069 43,170 64,135 Warrants 24,329 24,329 24,329 Stock options 8,723 11,177 20,420 Shares subject to repurchase and others 6,637 9,146 9,335 Since the Company expects to settle the principal amount of the outstanding 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. The conversion spread of 24.3 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 Notes. If the average market price of the common stock exceeds the exercise price of the warrants, $105.28, 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 $105.28, the warrants are anti-dilutive .

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Preferred Stock	Note 11. Preferred Stock Prior to the initial public offering, the Company had outstanding shares of Class A junior preferred stock and several series of convertible preferred stock. The 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, 2016 and 2015, there was no preferred stock outstanding.

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	12 Months Ended
	Dec. 31, 2016
Stockholders Equity Note [Abstract]
Common Stock and Stockholders' Equity	Note 12. Common Stock and Stockholders’ Equity Common Stock As of December 31, 2016, 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, 2016, no dividends have been declared. 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, 2016 are summarized as follows (in thousands, except per share data): Weighted-Average Number of Grant-Date Fair Shares Value Per Share Unvested restricted common stock at December 31, 2015 4,540 $ 33.88 Granted 3,320 $ 16.63 Vested (2,371 ) $ 32.94 Canceled (392 ) $ 34.46 Unvested restricted common stock at December 31, 2016 5,097 $ 23.04 Equity Incentive Plans The Company’s 2013 Equity Incentive Plan became effective upon the completion of the Company’s initial public offering and 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, 2016, the total number of options and RSUs outstanding under the 2013 Equity Incentive Plan was 46.3 million shares, and 123.0 million shares were available for future issuance. There were 9.1 million shares of options and RSUs outstanding under the 2007 Equity Incentive Plan as of December 31, 2016. No additional shares have been issued under the 2007 Equity Incentive Plan since 2013. 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. On May 25, 2016, the Company’s stockholders approved the 2016 Equity Incentive Plan. A total of 6,814,085 shares were reserved under the 2016 Equity Incentive Plan, which equals the number of shares that the Jack Dorsey Revocable Trust dated December 8, 2010 (the “Jack Dorsey Trust”), for which Jack Dorsey, the Company’s Chief Executive Officer, serves as trustee, gave back and contributed to the Company without any cost or charge to the Company. All such shares have been retired and cancelled by the Company. A maximum aggregate number of 6,814,085 shares were reserved under the 2016 Equity Incentive Plan and are available for grants. 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. Employee Stock Purchase Plan On November 7, 2013, the Company’s 2013 Employee Stock Purchase Plan (the “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 2013 Employee Stock Purchase Plan 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, 2016 and 2015, employees purchased an aggregate of 2.0 million and 1.5 million shares, respectively, under this plan at a weighted average price of $11.98 and $25.78 per share, respectively. Stock Option Activity A summary of stock option activity for the year ended December 31, 2016 is as follows (in thousands, except years and per share data): Options Outstanding Weighted- Weighted- Average Average Remaining Number of Exercise Contractual Life Aggregate Shares Price Per Share (in years) Intrinsic Value Outstanding at December 31, 2015 11,177 $ 6.55 5.86 $ 199,576 Options granted and assumed in connection with acquisitions 557 $ 3.23 Options exercised (2,864 ) $ 2.56 Options canceled (147 ) $ 3.50 Outstanding at December 31, 2016 8,723 $ 7.71 4.25 $ 98,240 Vested and expected to vest at December 31, 2016 (1) 8,147 $ 6.97 3.94 $ 94,712 Exercisable at December 31, 2016 6,962 $ 5.37 3.24 $ 85,916 (1) The expected to vest options are the result of applying pre-vesting forfeiture rate assumptions to unvested options outstanding. 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, 2016, 2015 and 2014 were $41.4 million, $337.2 million and $872.8 million, respectively. Performance Restricted Stock Units (“PRSUs”) Activity In 2016, the Company granted PRSUs to certain of its executive officers and established the 2016 annual performance goals for these PRSUs. The PRSUs will vest based on the Company’s attainment of the annual financial performance goals and the executives’ continued employment through the vesting date, approximately one year. The number of shares that ultimately vest for 2016 was estimated to be 70 percent of the annual target amount, based on the Company’s performance, subject to the Compensation Committee of the Board of Director’s approval. RSU Activity The following table summarizes the activity related to the Company’s RSUs for the year ended December 31, 2016. 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 Weighted- Average Grant- Date Fair Value Shares Per Share Unvested and outstanding at December 31, 2015 43,170 $ 32.46 Granted 51,231 $ 16.15 Vested (26,918 ) $ 23.70 Canceled (19,414 ) $ 25.88 Unvested and outstanding at December 31, 2016 48,069 $ 22.64 The total fair value of RSUs vested during the years ended December 31, 2016 and December 31, 2015 was approximately $466.4 million and $849.8 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 for the years ended December 31, 2016, 2015 and 2014 is as follows (in thousands): Year Ended December 31, 2016 2015 2014 Cost of revenue $ 29,502 $ 40,705 $ 50,536 Research and development 335,498 401,537 360,726 Sales and marketing 160,935 156,904 157,263 General and administrative 89,298 82,972 63,072 Total stock-based compensation expense $ 615,233 $ 682,118 $ 631,597 During 2014, the Company modified the terms of stock options and RSUs for certain employees upon their termination or change in employment status. The Company recorded incremental stock-based compensation in relation to the modification of stock-based awards of approximately $32.6 million in the year ended December 31, 2014. 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, 2016 and 2015. Income tax benefits recognized for stock-based compensation arrangements during the years ended December 31, 2016, 2015 and 2014 were not material. The Company capitalized $73.9 million, $50.3 million and $40.8 million of stock-based compensation expense associated with the cost for developing software for internal use in the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016, there was $844.0 million of unamortized stock-based compensation expense related to unvested awards which is expected to be recognized over a weighted-average period of 2.18 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Note 13. Income Taxes The domestic and foreign components of pre-tax loss for the years ended December 31, 2016, 2015 and 2014 are as follows (in thousands): Year Ended December 31, 2016 2015 2014 Domestic $ (237,325 ) $ (201,628 ) $ (164,854 ) Foreign (203,509 ) (331,677 ) (413,497 ) Loss before income taxes $ (440,834 ) $ (533,305 ) $ (578,351 ) The components of the provision (benefit) for income taxes for the years ended December 31, 2016, 2015 and 2014 are as follows (in thousands): Year Ended December 31, 2016 2015 2014 Current: Federal $ 1,087 $ — $ — State (143 ) 1,226 720 Foreign 19,870 14,625 8,358 Total current provision for income taxes 20,814 15,851 9,078 Deferred: Federal 293 (23,208 ) (8,972 ) State 17 (852 ) (128 ) Foreign (5,085 ) (4,065 ) (509 ) Total deferred benefit for income taxes (4,775 ) (28,125 ) (9,609 ) Provision (benefit) for income taxes $ 16,039 $ (12,274 ) $ (531 ) The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2016, 2015 and 2014: Year Ended December 31, 2016 2015 2014 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 0.0 (0.1 ) (0.1 ) Stock-based compensation (2.3 ) (2.9 ) (4.2 ) Research and development credits 6.6 7.2 25.2 Valuation Allowance (7.0 ) 3.1 (9.4 ) Nondeductible expenses (7.0 ) (5.6 ) (4.5 ) Foreign rate differential (19.5 ) (23.7 ) (26.4 ) Change in tax positions (9.5 ) (10.7 ) (15.9 ) Other 0.1 0.0 0.4 Effective tax rate (3.6 )% 2.3 % 0.1 % The tax effects of temporary differences and related deferred tax assets and liabilities as of December 31, 2016 and 2015 are as follows (in thousands): December 31, 2016 2015 Deferred tax assets: Net operating loss carryforwards $ 235,668 $ 242,987 Accruals and reserves 61,594 36,133 Stock-based compensation expense 64,136 80,106 Research and development credits 251,808 209,425 California Enterprise Zone Credit 12,266 11,710 Fixed assets and intangible assets 2,631 1,457 Other 11,980 7,059 Total deferred tax assets 640,083 588,877 Valuation allowance (439,993 ) (378,448 ) Total deferred tax assets, net of valuation allowance 200,090 210,429 Deferred tax liabilities: Fixed assets and intangible assets (168,223 ) (174,007 ) Convertible notes (24,303 ) (30,002 ) Other (1,612 ) (1,577 ) Total deferred tax liabilities (194,138 ) (205,586 ) Net deferred tax assets $ 5,952 $ 4,843 Based on the available objective evidence, management believes it is more-likely-than-not that the net U.S. and Brazil deferred tax assets were not fully realizable as of the year ended December 31, 2016. Accordingly, the Company has established a full valuation allowance against its U.S. and Brazil deferred tax assets. As of December 31, 2016, the Company has net $6.6 million of deferred tax assets in foreign jurisdictions which it believes are more-likely-than-not to be fully realized given the expectation of future earnings in these jurisdictions. For the year ended December 31, 2016, the Company has not provided for income taxes on $157.1 million of its undistributed earnings for certain foreign subsidiaries because these earnings are intended to be indefinitely reinvested in operations outside the U.S. Determining the unrecognized deferred tax liabilities associated with these earnings is not practicable. At December 31, 2016, the Company had $3.47 billion of federal and $1.41 billion of state net operating loss carryforwards available to reduce future taxable income, which will begin to expire in 2027 for federal and 2017 for state tax purposes. Pursuant to authoritative guidance, effective through December 31, 2016, the excess benefit from stock-based compensation was recorded to stockholders’ equity when cash taxes payable were reduced. As of December 31, 2016, the portion of net operating loss carryforwards related to the excess tax benefit from stock-based compensation was approximately $3.42 billion The Company also has research credit carryforwards of $222.8 million and $184.5 million for federal and state income tax purposes, respectively. The federal credit carryforward will begin to expire in 2027. The state research tax credits have no expiration date. Additionally, the Company has California Enterprise Zone Credit carryforwards of $18.9 million which will begin to expire in 2023. Utilization of the net operating loss carryforwards and credits 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, 2016, the unrecognized tax benefit was $269.5 million, including $263.7 million of unrecognized tax benefits which, if recognized, will not affect the annual effective tax rate as these unrecognized tax benefits would increase deferred tax assets which would be subject to a full valuation allowance, and the remaining $5.8 million of unrecognized tax benefits which, if recognized, would affect the annual effective tax rate. A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows (in thousands): Year Ended December 31, 2016 2015 2014 Balance at the beginning of the year $ 209,443 $ 182,484 $ 43,061 Additions related to prior year tax positions 3,682 1,820 — Reductions related to prior year tax positions — (45,305 ) (50 ) Additions related to current year tax positions 56,383 70,444 139,473 Balance at the end of the year $ 269,508 $ 209,443 $ 182,484 Total unrecognized tax benefits are recorded on the Company’s consolidated balance sheets as follows (in thousands): December 31, 2016 2015 Total unrecognized tax benefits balance $ 269,508 $ 209,443 Amounts netted against related deferred tax assets (263,696 ) (208,307 ) Unrecognized tax benefits recorded on consolidated balance sheets $ 5,812 $ 1,136 The net unrecognized tax benefit of $5.8 million and $1.1 million as of December 31, 2016 and 2015, respectively, was included in the deferred and other long-term tax liabilities, net on the Company’s consolidated balance sheets. The Company does not believe that its unrecognized tax benefits will significantly change within the next 12 months. The Company recognizes interest and/or penalties related to income tax matters as a component of income tax expense. As of December 31, 2016 there were no significant accrued interest and penalties related to uncertain tax positions. On July 27, 2015, the United State Tax Court issued an opinion (Altera Corp. et al. v. Commissioner), which invalidated the 2003 final Treasury rule that requires participants in qualified cost-sharing arrangements to share stock-based compensation costs. As such, the Company filed its 2014 and 2015 federal tax returns based upon the opinion rendered in this case, which resulted in an increase in the 2014 and 2015 net operating losses in the U.S jurisdiction. As the Company maintains a full valuation allowance on its US deferred tax assets, no benefit was realized in the financial statements as a result of this filing position. The Company is subject to taxation in the United States and various state and foreign jurisdictions. Earnings from non-US activities are subject to local country income tax. The material jurisdictions in which the Company is subject to potential examination by taxing authorities include the United States, California and Ireland. The Company is currently under a Federal income tax examination by the Internal Revenue Service (IRS) for tax years 2011, 2012 and 2013. The Company believes that adequate amounts have been reserved in these jurisdictions. The Company’s 2007 to 2016 tax years remain subject to examination by the United States and California, and its 2011 to 2016 tax years remain subject to examination in Ireland. The Company remains subject to possible examination in various other jurisdictions that are not expected to result in material tax adjustments.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 14. Commitments and Contingencies Credit Facility The Company entered into a revolving credit agreement with certain lenders in 2013, which provided for a $1.0 billion revolving unsecured credit facility maturing on October 22, 2018. Loans under the credit facility bear interest, at the Company’s option, at (i) a base rate based on the highest of the prime rate, the federal funds rate plus 0.50% and an adjusted LIBOR rate for a one-month interest period plus 1.00%, in each case plus a margin ranging from 0.00% to 0.75% or (ii) an adjusted LIBOR rate plus a margin ranging from 1.00% to 1.75%. This margin is determined based on the total leverage ratio for the preceding four fiscal quarter period. The Company is obligated to pay other customary fees for a credit facility of this size and type, including an upfront fee and an unused commitment fee. Obligations under the credit facility are guaranteed by one of the Company’s wholly-owned subsidiaries. In addition, the credit facility contains restrictions on payments including cash payments of dividends. The revolving credit agreement was amended in September 2014 to increase the amount of indebtedness that the Company may incur and increase the amount of restricted payments that the Company may make. This amendment to the revolving credit agreement also provides that if the Company’s total leverage ratio exceeds 2.5:1.0 and if the amount outstanding under the credit facility exceeds $500.0 million, or 50% of the amount that may be borrowed under the credit facility, the credit facility will become secured by substantially all of the Company’s and certain of its subsidiaries’ assets, subject to limited exceptions. As of December 31, 2016, no amounts were drawn under the credit facility. Operating and Capital Leases The Company has entered into various non-cancelable operating lease agreements for certain offices and data center facilities with contractual lease periods expiring between 2017 and 2028. During the year ended December 31, 2016, the Company entered into several sublease agreements for the office space that the Company not fully utilizing. The Company also has lease arrangements for certain server and networking equipment. A summary of gross lease commitments and sublease income as of December 31, 2016 is as follows (in thousands): Operating Sublease Capital Leases Income Leases Years ending December 31, 2017 $ 156,757 $ (24,101 ) $ 85,886 2018 148,157 (23,712 ) 45,984 2019 116,189 (16,577 ) 21,062 2020 90,664 (9,038 ) — 2021 57,937 (8,969 ) — Thereafter 163,315 — — $ 733,019 $ (82,397 ) 152,932 Less: Amounts representing interest 5,247 Total capital lease obligation 147,685 Less: Short-term portion 80,848 Long-term portion $ 66,837 Rent expense, net of sublease income, under the Company’s operating leases, including co-location arrangements for the Company’s data centers, was $155.7 Non-cancelable Obligations The Company also had $138.4 million of non-cancelable contractual commitments as of December 31, 2016, primarily related to its infrastructure services, bandwidth and other services arrangements. These commitments are generally due within one to three years. Legal Proceedings The Company is currently involved in, and may in the future be involved in, legal proceedings, claims and governmental investigations in the normal course of business. These proceedings, in the form of both individual and class action litigation, have included, but are not limited to matters involving intellectual property, defamation, privacy, 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. Litigation accruals are recorded when and if it is determined that a loss related matter is both probable and reasonably estimable. Material loss contingencies that are reasonably possible of occurrence, if any, are subject to disclosure. As of December 31, 2016, there was no litigation or contingency with at least a reasonable possibility of a material loss. No material losses have been recorded during the years ended December 31, 2016, 2015 and 2014 with respect to litigation or loss contingencies. 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, 2016 and 2015.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Party Transactions	Note 15. Related Party Transactions In September 2015, the Company entered into a partnership agreement for no consideration with Square, Inc., for which Jack Dorsey (the Company’s Chief Executive Officer) serves as Chief Executive Officer, to enable U.S. political donations through Tweets. Neither Square, Inc. nor the Company will pay each other any amounts in connection with the agreement. The agreement has no impact on the Company’s financial statements. On October 22, 2015, the Company and the Jack Dorsey Revocable Trust dated December 8, 2010 (the “Jack Dorsey Trust”), for which Jack Dorsey (the Company’s Chief Executive Officer) serves as trustee, entered into a Contribution Agreement that the Jack Dorsey Trust will give back and contribute to Twitter, without any cost or charge, an aggregate of 6,814,085 shares of Twitter’s common stock upon the Company’s stockholders approval of an equity incentive plan. On May 25, 2016, the Company’s stockholders approved the 2016 Equity Incentive Plan with the same number of shares to be granted over time to employees, non-employee directors and consultants. All the shares contributed from the Jack Dorsey Trust have been retired and cancelled by the Company.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plan	Note 16. Employee Benefit Plan The Company adopted a 401(k) Plan that qualifies as a deferred compensation arrangement under Section 401 of the Code. Under the 401(k) Plan, participating employees may defer a portion of their pretax earnings not to exceed the maximum amount allowable. The Company made discretionary matching contributions to those participating employees who met certain employment criteria. The matching contributions made by the Company to date was not material.

Segment Information and Operati

Segment Information and Operations by Geographic Area	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segment Information and Operations by Geographic Area	Note 17. 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 Revenue by geography is based on the billing addresses of the customers. The following tables set forth revenue by services and revenue by geographic area (in thousands): Year Ended December 31, 2016 2015 2014 Revenue by services: Advertising services $ 2,248,052 $ 1,994,036 $ 1,255,688 Data licensing and other 281,567 223,996 147,314 Total revenue $ 2,529,619 $ 2,218,032 $ 1,403,002 Year Ended December 31, 2016 2015 2014 Revenue by geographic area: United States $ 1,564,776 $ 1,443,240 $ 945,720 International 964,843 774,792 457,282 Total revenue $ 2,529,619 $ 2,218,032 $ 1,403,002 Japan accounted for $268.5 million, or 11% of total revenue for the year ended December 31, 2016. Property and Equipment, net The following table sets forth property and equipment, net by geographic area (in thousands): December 31, December 31, 2016 2015 Property and equipment, net: United States $ 728,429 $ 683,176 International 55,472 52,123 Total property and equipment, net $ 783,901 $ 735,299

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2016
Restructuring And Related Activities [Abstract]
Restructuring Charges	Note 18. Restructuring Charges On October 25, 2016, the Board of Directors of the Company approved a reduction in force plan (“2016 Plan”) of up to approximately 9% of the Company’s positions globally. The reduction in force was undertaken to eliminate investment in noncore areas and drive toward greater efficiency, while allowing the Company to continue to invest in its highest priorities. The Company expects the reduction in force to be completed in 2017. On December 17, 2016, the Board of Directors of the Company approved a lease abandonment plan (“2016 Lease Plan”) to abandon excess office space with lease terms expiring through 2028. For the year ended December 31, 2015, the Company incurred total restructuring expense of $12.9 million in connection with the reduction in force plan, which was substantially completed in 2015. The following table summarizes the restructuring charges for the year ended December 31, 2016 and related liabilities as of December 31, 2016 (in thousands): 2016 Employee 2016 Termination Plan Lease Plan Charges $ 21,611 $ 79,685 Cash payment (11,629 ) (3,562 ) Non-cash and other adjustments (6,357 ) (19,577 ) Accrued as of December 31, 2016 $ 3,625 $ 56,546 Cost of revenue $ 13 $ 49,006 Research and development 4,246 11,693 Sales and marketing 17,310 13,072 General and administrative 42 5,914 Total costs incurred in 2016 $ 21,611 $ 79,685 Reflected in consolidated balance sheets: (1) Accrued and other current liabilities $ 3,625 $ 52,317 Other long-term liabilities $ — $ 4,229 (1)

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2016
Valuation And Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	PART IV Item 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES The following documents are filed as part of this Annual Report on Form 10-K: 1. Consolidated Financial Statements Our Consolidated Financial Statements are listed in the “Index to Consolidated Financial Statements” under Part II, Item 8 of this Annual Report on Form 10-K. 2. Financial Statement Schedules SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS FOR THE YEARS ENDED DECEMBER 31, 2016, 2015 AND 2014 Charged/ Balance at Credited Beginning of Charged to to Other Balance at Year Expenses Accounts End of Year (In thousands) Allowance for Deferred Tax Assets: Year ended December 31, 2016 $ 378,448 $ 57,529 $ 4,016 $ 439,993 Year ended December 31, 2015 $ 351,249 $ 27,175 $ 24 $ 378,448 Year ended December 31, 2014 $ 227,878 $ 155,111 $ (31,740 ) $ 351,249 Balance at Beginning of Additions Write-off/ Balance at Year (Reductions) Adjustments End of Year (In thousands) Allowance for Doubtful Accounts: Year ended December 31, 2016 $ 8,121 $ 3,958 $ (4,863 ) $ 7,216 Year ended December 31, 2015 $ 5,507 $ 5,765 $ (3,151 ) $ 8,121 Year ended December 31, 2014 $ 2,020 $ 4,632 $ (1,145 ) $ 5,507 All other financial statement schedules have been omitted because they are not required, not applicable, not present in amounts sufficient to require submission of the schedule, or the required information is shown in our Consolidated Financial Statements or Notes thereto. 3. Exhibits The documents listed in the Exhibit Index of this Annual Report on Form 10-K are incorporated by reference or are filed with this Annual Report on Form 10-K, in each case as indicated therein (numbered in accordance with Item 601 of Regulation S-K). Item 16. FORM 10-K SUMMARY None.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
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 significant intercompany accounts and transactions have been eliminated in consolidation.
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. Certain prior period amounts have been reclassified to conform to the current period presentation.
Revenue Recognition	Revenue Recognition The Company generates the substantial majority of its revenue from the sale of advertising services and, to a lesser extent, from entering into data licensing and other arrangements. The Company’s advertising services include three primary products: (i) Promoted Tweets, (ii) Promoted Accounts and (iii) Promoted Trends. Promoted Tweets and Promoted Accounts are pay-for-performance advertising products 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 user engages with a Promoted Tweet or follows a Promoted Account or when a Promoted Trend is displayed. These products may be sold in combination as a multiple element arrangement or separately on a stand-alone basis. The Company also generates advertising revenue by selling to advertisers advertising products which it places 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 it has identified the advertisers’ targeted audience and therefore incurs traffic acquisition costs. In such transactions, the Company remains the primary obligor to its advertisers for the advertising services and products delivered, has pricing latitude, has discretion in the selection of third party publishers and bears credit risk. The Company might not generate advertising revenue in excess of traffic acquisition costs incurred. Therefore, the Company reports advertising revenue generated from these transactions on a gross basis. Fees for these advertising services are recognized in the period when advertising is delivered as evidenced by a user engaging with a Promoted Tweet in a manner satisfying the types of engagement selected by the advertisers, such as Tweet engagements (e.g., retweets, replies and likes), website clicks or conversions, mobile application installs or engagements, obtaining new followers, or video views, following a Promoted Account, through the display of a Promoted Trend on the Company’s platform, or completion of a transaction on an external website. Data licensing revenue is generated based on monthly service fees charged to the data partners over the period in which the Company’s data and data products are made available to them. 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 and matches buyers and sellers. 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. Therefore, the Company reports revenue related to its ad exchange services on a net basis. Revenue is recognized only when (1) persuasive evidence of an arrangement exists; (2) the price is fixed or determinable; (3) the service is performed; and (4) collectability of the related fee is reasonably assured. 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 elements. For arrangements involving multiple deliverables, judgment is required to determine the appropriate accounting, including developing an estimate of the stand-alone selling price of each deliverable. When neither vendor-specific objective evidence nor third-party evidence of selling price exists, the Company uses its best estimate of selling price (BESP) to allocate the arrangement consideration on a relative selling price basis to each deliverable. The objective of BESP is to determine the selling price of each deliverable when it is sold to advertisers on a stand-alone basis. In determining BESPs, the Company takes into consideration various factors, including, but not limited to, prices the Company charges for similar offerings, sales volume, geographies, pricing strategies and market conditions. Multiple deliverable arrangements 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 selling price for these products in order to allocate any potential discount to all advertising products in the arrangement. The estimate of selling price for pay-for-performance products is determined based on the winning bid price; the estimate of selling price for Promoted Trends is based on Promoted Trends sold on a stand-alone basis and/or separately priced in a bundled arrangement by reference to a list price by geography which is approved periodically. The Company believes the use of BESP results in revenue recognition in a manner consistent with the underlying economics of the transaction and allocates the arrangement consideration on a relative selling price basis to each deliverable.
Cost of Revenue	Cost of Revenue Cost of revenue includes infrastructure costs, other direct costs including content costs, amortization expense of technology acquired through acquisitions and capitalized labor costs, 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, as well as depreciation of its servers and networking equipment, and personnel-related costs, including salaries, benefits and stock-based compensation, for its operations teams. 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 and from the Company’s organically-built advertising network, Twitter Audience Platform.
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. The Company recognizes the compensation expense only for those awards expected to meet the performance and service vesting condition on a straight-line basis over the requisite service period which is generally one year for performance vesting condition awards and four years for service vesting condition awards. 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. Calculating the fair value using the Black-Scholes model requires various judgmental assumptions including the expected term and stock price volatility. The Company estimates the expected term of stock options granted based on the simplified method. The Company estimates the expected volatility of its common stock on the dates of grant based on a combination of the Company’s historical stock price volatility and implied volatility in the Company’s traded options when such information is available. When the Company’s historical and implied volatility data are not available for the related awards’ expected term, an average of volatility rates including the historical volatility of a group of comparable, publicly-traded companies is used. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. Expected dividend yield is zero percent as the Company has not paid and does not anticipate paying dividends on its common stock. 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 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. Stock-based compensation expense is recorded net of estimated forfeitures. Through 2016, the Company estimated the forfeiture rate based on historical forfeitures of stock-based awards and adjusted the rate to reflect changes in facts and circumstances, if any.
Acquisitions	Acquisitions The Company accounts for acquisitions of entities that include inputs and processes and have the ability to create outputs as business combinations. The purchase price of the acquisition is allocated 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 and assesses the accounting for these investments under the equity or cost method. 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 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 determines the fair value by reviewing equity valuation reports, current financial results and long-term plans of the private companies.
Restructuring and Other Charges	Restructuring and Other Charges The Company records charges associated with management-approved restructuring plans to reduce headcount and for leases. Restructuring costs are recognized when the related liability is incurred and measured at fair value. The Company accrues a liability for employee terminations when all of the following conditions have been met: management, having the authority to approve the action, commits to a plan of termination; the plan identifies the number of employees to be terminated, their job classifications and their locations, and the expected completion date; the plan establishes the terms of the benefit arrangement in sufficient detail to enable employees to determine the type and amount of benefits they will receive if they are involuntarily terminated; and actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. The Company accrues for costs to terminate an operating lease or other contract when it terminates the contract in accordance with the contract terms. A liability for costs that will continue to be incurred under a contract for the remaining term without economic benefits to the Company is recognized and measured when the entity meets the cease-use date. In recording liabilities for cease-use facilities, the Company makes various assumptions, including the time period over which the facilities are expected to be vacant, expected sublease terms and expected sublease rates. The estimates involve a number of risks and uncertainties, some of which are beyond the Company’s control, including future real estate market conditions and the Company’s ability to successfully enter into sublease agreements with terms as favorable as those assumed when arriving at the estimates. The Company regularly evaluates a number of factors to determine the appropriateness and reasonableness of the restructuring and lease loss accruals including the various assumptions noted above. If actual results differed significantly from its estimates, the Company may be required to adjust the restructuring and lease loss accruals in the future.
Operating and Capital Leases	Operating and Capital Leases The Company leases office space and data center facilities under operating leases. Certain lease agreements contain free or escalating rent payment provisions. The Company recognizes rent expense under such leases on a straight-line basis over the term of the lease. Lease renewal periods are considered on a lease-by-lease basis in determining the lease term. The Company also has entered into server and networking equipment lease arrangements with original lease terms ranging from three to four years. The Company’s server and networking equipment leases typically are accounted for as capital leases as they meet one or more of the four capital lease classification criteria. Assets acquired under capital leases are amortized over their estimated useful life. As of December 31, 2016 and 2015, the Company had capital lease obligations included in short-term and long-term capital lease obligations in the consolidated balance sheets of $147.7 million and $147.9 million, respectively. In the years ended December 31, 2016, 2015 and 2014, the Company recorded approximately $5.5 million, $8.8 million and $10.2 million, respectively, of interest expense in relation to these capital lease arrangements.
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, 2016 and 2015, the Company has recorded restricted cash balances of $9.4 million and $3.0 million, respectively, within prepaid expenses and other current assets and $29.6 million and $31.1 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, and reports the unrealized gains and losses, net of taxes, as a component of stockholders’ equity, except for unrealized losses determined to be other-than-temporary which are recorded as other income (expense), net. 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 $24.3 million, $9.1 million, and $1.9 million during the years ended December 31, 2016, 2015 and 2014, respectively. These balances are recorded in other income (expense), net in the accompanying consolidated statements of operations. The Company evaluates the investments periodically for possible other-than-temporary impairment. A decline in fair value below the amortized costs of debt securities is considered an other-than-temporary impairment if the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security before recovery of the entire amortized cost basis. In those instances, an impairment charge equal to the difference between the fair value and the amortized cost basis is recognized in earnings. Regardless of the Company’s intent or requirement to sell a debt security, impairment is considered other-than-temporary if the Company does not expect to recover the entire amortized cost basis.
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 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, 2016 and 2015, no single customer accounted for more than 10% of the Company’s net accounts receivable balance. No single customer accounted for more than 10% of the Company’s revenue in the years ended December 31, 2016, 2015 and 2014. The Company’s note hedge transactions, entered into in connection with the Notes, as defined and further described in Note 4— Fair Value Measurements
Accounts Receivable, Net	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, and the customer’s current financial condition.
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 to five years Computer software One to four years Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term 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 Interest Interest costs is capitalized for assets that are constructed for the Company’s own internal use, this includes internally developed software and property and equipment, for the period of time to get them ready for its intended use. During the years ended December 31, 2016 and 2015, the Company capitalized $4.3 million and $5.0 million of interest expense, respectively. Capitalized interest was not material in 2014.
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, the second step of the test is performed by comparing the carrying value of the goodwill in the reporting unit to its implied fair value. An impairment charge is recognized for the excess of the carrying value of goodwill over its implied fair value. The Company conducted its annual goodwill impairment test during the fourth quarter of 2016 and determined that goodwill was not impaired. As such, no impairment charge was recorded in any of the periods presented in the accompanying consolidated financial statements.
Intangible Assets	Intangible Assets Intangible 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. There has been no impairment charges recorded in any of the periods presented in the accompanying consolidated financial statements.
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. In the years ended December 31, 2016, 2015 and 2014, the Company capitalized costs totaling approximately $139.0 million, $92.8 million and $79.5 million, respectively. The estimated useful life of costs capitalized is evaluated for each specific project and is one to four years. In the years ended December 31, 2016, 2015 and 2014, the amortization of capitalized costs included in cost of revenue totaled approximately $74.6 million, $37.8 million and $15.2 million, respectively.
Income Taxes	Income Taxes The Company accounts for its income taxes using the asset and liability method whereby deferred tax assets and liabilities are determined based on temporary differences between the bases used for financial reporting and income tax reporting purposes, as well as for operating loss and tax credit carryforwards. Deferred income taxes are provided based on the enacted tax rates expected to be in effect at the time such temporary differences are expected to reverse. A valuation allowance is provided for deferred tax assets if it is more-likely-than-not that the Company will not realize those tax assets through future operations. The Company evaluates and accounts for uncertain tax positions using a two-step approach. Recognition (step one) occurs when the Company concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustainable upon examination. Measurement (step two) determines the amount of benefit that is greater than 50% likely to be realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. De-recognition of a tax position that was previously recognized would occur when the Company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. Although the Company believes that it has adequately reserved for uncertain tax positions, the Company can provide no assurance that the final tax outcome of these matters will not be materially different. The Company makes adjustments to these reserves when facts and circumstances change, such as the closing of a tax audit, the lapsing of a statute, or the refinement of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made and could have a material impact on the Company’s financial position and results of operations.
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 Costs Advertising costs are expensed when incurred and are included in sales and marketing expense in the accompanying consolidated statements of operations. Advertising expense totaled $114.3 million, $119.7 million and $46.6 million for the years ended December 31, 2016, 2015 and 2014 respectively.
Comprehensive Loss	Comprehensive Loss Comprehensive loss consists of two components, net 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 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 pronouncement In June 2014, the Financial Accounting Standards Board (“FASB”) issued a new accounting standard update on stock-based compensation when the terms of an award provide that a performance target could be achieved after the requisite service period. The new guidance requires that a performance target that affects vesting, and that could be achieved after the requisite service period, be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. This update further clarifies that compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the periods for which the requisite service has already been rendered. The Company adopted this guidance prospectively during the year ended December 31, 2016, and the adoption had no impact to the Company’s financial statements. In February 2015, the FASB issued a new accounting standard update on consolidation analysis. The new guidance amends the current consolidation guidance with respect to the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. This guidance became effective for reporting periods beginning after December 15, 2015. The Company adopted this guidance retrospectively during the year ended December 31, 2016, and the adoption had no impact on the Company’s financial statements. In April 2015, the FASB issued a new accounting standard update on the presentation of debt issuance costs. The new guidance requires the debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. The Company adopted this guidance retrospectively during the year ended December 31, 2016 and the adoption had an immaterial impact on the Company’s financial statements. In September 2015, the FASB issued a new accounting standard update on simplifying the accounting for measurement-period adjustments in business combinations. The new guidance requires that the adjustments to provisional amounts that are identified during the measurement period be recognized in the reporting period when the adjustments are determined. In addition, the effect on earnings of changes as a result of the change to the provisional amounts is required to be recorded in the same period’s financial statements. The Company adopted this guidance prospectively on January 1, 2016, and the adoption had no impact on the Company’s financial statements. Recently issued accounting pronouncements not yet adopted In May 2014, the FASB issued a new accounting standard update on revenue recognition from contracts with customers. The new guidance will replace all current GAAP guidance on this topic and eliminate industry-specific guidance. According to the new guidance, revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration for which the Company expects to be entitled in exchange for those goods or services. The guidance will be effective for fiscal years and interim periods with those fiscal years, beginning after December 15, 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. In March 2016, April 2016, May 2016 and December 2016, the FASB further amended the guidance to clarify the implementation on principal versus agent considerations, the identification of performance obligation and the licensing implementation guidance, to provide narrow-scope improvements and practical expedients, and technical corrections and improvements. The Company will adopt this standard effective January 1, 2018 and currently anticipates adopting the standard using the modified retrospective method. The Company is still in the process of completing its analysis of the impact this standard will have on the consolidated financial statements. Specifically, while the Company has not yet finalized its analysis of the recognition impact this standard will have on advertising revenue, the Company does not expect the impact to be material; the Company is still assessing the recognition impact of adopting this standard on data licensing and other revenue; and the Company has not completed its assessment of the presentation impact of adoption of the new principal versus agent guidance on its arrangements. In January 2016, the FASB issued a new accounting standard update on the classification and measurement of financial instruments. The new guidance principally affects accounting standards for equity investments, financial liabilities where the fair value option has been elected, and the presentation and disclosure requirements for financial instruments. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted. The Company is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In February 2016, the FASB issued a new accounting standard update on leases. The new guidance requires lessees to recognize right-of-use assets and lease liabilities for operating leases, initially measured at the present value of the lease payments, on the balance sheet. In addition, it requires lessees to recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term, generally on a straight-line basis. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The Company is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures and anticipates this new guidance will materially impact the Company’s financial statements given the Company has a significant number of operating leases. In March 2016, the FASB issued a new accounting standard update on simplifying the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The new guidance also allows an entity to account for forfeitures when they occur. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Early adoption is permitted. The Company will adopt this new guidance during the three months ending March 31, 2017. Adoption will require all tax benefits in excess of stock-based compensation costs to be recorded in the consolidated statements of operations as a component of the provision for income taxes, whereas they are currently recorded in equity. This change is required to be applied prospectively to excess tax benefits resulting from settlements after the date of adoption. For excess tax benefits not previously recognized, the Company will be required to apply the modified retrospective method with a cumulative-effect adjustment to opening accumulated deficit. In the quarter ending March 31, 2017, the Company will recognize deferred tax assets for its accumulated net operating losses related to excess tax benefits as of December 31, 2016 not previously recognized. However, given the valuation allowance placed on substantially all of the deferred tax assets, the recognition upon adoption is not expected to have a material impact on the Company’s accumulated deficit. Additionally, the consolidated statements of cash flows will include excess tax benefits as an operating activity, with the prior periods adjusted accordingly, as a result of the adoption. Finally, the Company will elect to account for forfeitures as they occur, rather than estimate expected forfeitures. In June 2016, the 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted as early as of the fiscal years beginning after December 15, 2018. The Company is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In August 2016, the FASB issued a new accounting standard update on the statement of cash flows. The new guidance clarifies classification of certain cash receipts and cash payments in the statement of cash flows. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted. The Company is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In October 2016, the FASB issued a new accounting standard update on simplifying the accounting for income taxes related to intra-entity asset transfers. The new guidance requires an entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfers occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. The modified retrospective approach will be required for transition to the new guidance, with a cumulative-effect adjustment recorded in retained earnings as of the period of adoption. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted only in the first quarter of 2017. The Company is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In November 2016, the FASB issued a new accounting standard update on the presentation of restricted cash in the statement of cash flows. The new guidance requires an entity to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows, and an entity will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted. The Company is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In January 2017, the FASB issued a new accounting standard update on narrowing the definition of a business. The new guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted. The Company plans to early adopt this new accounting standard update during the three months ended March 31, 2017. Adoption is expected to have no impact on the Company’s financial statements. In January 2017, the FASB issued a new accounting standard update on simplifying the accounting for goodwill impairment. The new guidance eliminates the requirement to calculate the implied fair value of goodwill (i.e., Step 2 of the goodwill impairment test) to measure a goodwill impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. This guidance will be effective in fiscal year 2020 and will be applied prospectively. Early adoption is permitted for any impairment tests performed after January 1, 2017. The Company plans to early adopt this new accounting standard update during fiscal year 2017. Adoption is not expected to have a material impact on the Company’s financial statements.

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives of Property and Equipment	Property and Equipment Estimated Useful Life Computer hardware, networking and office equipment Three to five years Computer software One to four years Furniture and fixtures Five years Leasehold improvements Lesser of estimated useful life or remaining lease term

Cash, Cash Equivalents and Sh29

Cash, Cash Equivalents and Short-term Investments (Tables)	12 Months Ended
	Dec. 31, 2016
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, 2016 2015 Cash and cash equivalents: Cash $ 253,808 $ 300,363 Money market funds 422,515 141,700 U.S. government and agency securities including treasury bills 12,639 — Corporate notes, commercial paper and certificates of deposit 299,636 469,408 Total cash and cash equivalents $ 988,598 $ 911,471 Short-term investments: U.S. government and agency securities including treasury bills $ 1,183,768 $ 1,156,418 Corporate notes, commercial paper and certificates of deposit 1,602,213 1,427,459 Total short-term investments $ 2,785,981 $ 2,583,877
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 securities classified as short-term investments on the Company’s consolidated balance sheets as of December 31, 2016 and 2015 (in thousands): December 31, 2016 Gross Gross Gross Aggregated Amortized Unrealized Unrealized Estimated Costs Gains Losses Fair Value U.S. government and agency securities including treasury bills $ 1,185,274 $ 136 $ (1,642 ) $ 1,183,768 Corporate notes, commercial paper and certificates of deposit 1,603,048 114 (949 ) 1,602,213 Total available-for-sale securities classified as short-term investments $ 2,788,322 $ 250 $ (2,591 ) $ 2,785,981 December 31, 2015 Gross Gross Gross Aggregated Amortized Unrealized Unrealized Estimated Costs Gains Losses Fair Value U.S. government and agency securities including treasury bills $ 1,158,479 $ 6 $ (2,067 ) $ 1,156,418 Corporate notes, certificates of deposit and commercial paper 1,429,374 21 (1,936 ) 1,427,459 Total available-for-sale securities classified as short-term investments $ 2,587,853 $ 27 $ (4,003 ) $ 2,583,877
Contractual Maturities of Securities Classified as Available-for-Sale	The contractual maturities of securities classified as available-for-sale as of December 31, 2016 were as follows (in thousands): December 31, 2016 Due within one year $ 1,990,083 Due after one year through two years 795,898 Total $ 2,785,981

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
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, 2016 and 2015 based on the three-tier fair value hierarchy (in thousands): December 31, 2016 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 422,515 $ — $ — $ 422,515 Treasury bills 12,639 — — 12,639 Corporate notes — 7,387 — 7,387 Commercial paper — 292,249 — 292,249 Short-term investments: U.S. government securities — 657,502 — 657,502 Agency securities — 526,266 — 526,266 Corporate notes — 689,986 — 689,986 Commercial paper — 311,238 — 311,238 Certificates of deposit — 600,989 — 600,989 Other current assets: Foreign currency contracts — 1,955 — 1,955 Total $ 435,154 $ 3,087,572 $ — $ 3,522,726 Liabilities Other current liabilities: Foreign currency contracts — 500 — 500 Total $ — $ 500 $ — $ 500 December 31, 2015 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 141,700 $ — $ — $ 141,700 Commercial paper — 419,110 — 419,110 Certificates of deposit — 50,298 — 50,298 Short-term investments: Treasury bills 29,953 — — 29,953 U.S. government securities — 537,168 — 537,168 Agency securities — 589,297 — 589,297 Corporate notes — 693,593 — 693,593 Commercial paper — 229,965 — 229,965 Certificates of deposit — 503,901 — 503,901 Other current assets: Foreign currency contracts — 6,804 — 6,804 Total $ 171,653 $ 3,030,136 $ — $ 3,201,789 Liabilities Other current liabilities: Foreign currency contracts — 3,005 — 3,005 Total $ — $ 3,005 $ — $ 3,005
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): December 31, December 31, Balance Sheet Location 2016 2015 Assets Foreign currency contracts not designated as hedging instruments Other current assets $ 1,955 6,804 Liabilities Foreign currency contracts not designated as hedging instruments Other current liabilities 500 3,005 Total fair value of derivative instruments $ 1,455 $ 3,799

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	The following table presents the detail of property and equipment, net for the periods presented (in thousands): December 31, December 31, 2016 2015 Property and equipment, net Equipment $ 909,797 $ 720,421 Furniture and leasehold improvements 304,613 297,274 Capitalized software 353,163 211,241 Construction in progress 74,255 85,073 Total 1,641,828 1,314,009 Less: Accumulated depreciation and amortization (857,927 ) (578,710 ) Property and equipment, net $ 783,901 $ 735,299

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2016
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, 2014 $ 622,570 TellApart acquisition 394,989 Other acquisitions 106,198 Foreign currency translation adjustment (1,029 ) Balance as of December 31, 2015 $ 1,122,728 Acquisitions 74,186 Foreign currency translation adjustment (11,599 ) Balance as of December 31, 2016 $ 1,185,315
Schedule of Intangible Assets	The following table presents the detail of intangible assets for the periods presented (in thousands): Gross Carrying Accumulated Net Carrying Value Amortization Value December 31, 2016: Patents and developed technologies $ 122,611 $ (47,160 ) $ 75,451 Publisher and advertiser relationships 53,100 (33,217 ) 19,883 Total $ 175,711 $ (80,377 ) $ 95,334 December 31, 2015: Patents and developed technologies $ 132,444 $ (43,991 ) $ 88,453 Publisher and advertiser relationships 75,300 (23,803 ) 51,497 Assembled workforce 1,960 (1,714 ) 246 Other intangible assets 2,100 (1,281 ) 819 Total $ 211,804 $ (70,789 ) $ 141,015
Schedule of Estimated Future Amortization Expenses	Estimated future amortization expense as of December 31, 2016 is as follows (in thousands): Years ending December 31, 2017 $ 43,810 2018 18,855 2019 8,796 2020 6,523 2021 6,126 Thereafter 11,224 Total $ 95,334

Accrued and Other Current Lia33

Accrued and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
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, 2016 2015 Accrued compensation $ 82,354 $ 90,906 Accrued restructuring 55,942 396 Accrued publisher, content and ad network costs 44,362 23,486 Deferred revenue 33,659 23,674 Accrued tax liabilities 29,558 25,880 Accrued sales and marketing expenses 22,431 27,948 Accrued other 112,631 91,502 Total $ 380,937 $ 283,792

Convertible Notes (Tables)

Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Components of Notes	The Notes consisted of the following (in thousands): December 31, 2016 December 31, 2015 2019 Notes 2021 Notes 2019 Notes 2021 Notes Principal amounts: Principal $ 935,000 $ 954,000 $ 935,000 $ 954,000 Unamortized initial purchasers' discount and debt discount (1) (136,376 ) (213,657 ) (181,994 ) (251,911 ) Net carrying amount $ 798,624 $ 740,343 $ 753,006 $ 702,089 Carrying amount of the equity component (2) $ 222,826 $ 283,283 $ 222,826 $ 283,283 (1) (2)

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss per share for periods presented (in thousands, except per share data). Year Ended December 31, 2016 2015 2014 Net loss $ (456,873 ) $ (521,031 ) $ (577,820 ) Basic shares: Weighted-average common shares outstanding 708,010 670,132 613,944 Weighted-average restricted stock subject to repurchase (5,875 ) (7,708 ) (8,954 ) Weighted-average shares used to compute basic net loss per share 702,135 662,424 604,990 Diluted shares: Weighted-average shares used to compute diluted net loss per share 702,135 662,424 604,990 Net loss per share attributable to common stockholders: Basic $ (0.65 ) $ (0.79 ) $ (0.96 ) Diluted $ (0.65 ) $ (0.79 ) $ (0.96 )
Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following number of potential common shares at the end of each period were excluded from the calculation of diluted net 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, 2016 2015 2014 RSUs 48,069 43,170 64,135 Warrants 24,329 24,329 24,329 Stock options 8,723 11,177 20,420 Shares subject to repurchase and others 6,637 9,146 9,335

Common Stock and Stockholders36

Common Stock and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2016
Stockholders Equity Note [Abstract]
Summary of Restricted Stock Activity	The activities for the restricted common stock issued to employees for the year ended December 31, 2016 are summarized as follows (in thousands, except per share data): Weighted-Average Number of Grant-Date Fair Shares Value Per Share Unvested restricted common stock at December 31, 2015 4,540 $ 33.88 Granted 3,320 $ 16.63 Vested (2,371 ) $ 32.94 Canceled (392 ) $ 34.46 Unvested restricted common stock at December 31, 2016 5,097 $ 23.04
Summary of Stock Option Activity	A summary of stock option activity for the year ended December 31, 2016 is as follows (in thousands, except years and per share data): Options Outstanding Weighted- Weighted- Average Average Remaining Number of Exercise Contractual Life Aggregate Shares Price Per Share (in years) Intrinsic Value Outstanding at December 31, 2015 11,177 $ 6.55 5.86 $ 199,576 Options granted and assumed in connection with acquisitions 557 $ 3.23 Options exercised (2,864 ) $ 2.56 Options canceled (147 ) $ 3.50 Outstanding at December 31, 2016 8,723 $ 7.71 4.25 $ 98,240 Vested and expected to vest at December 31, 2016 (1) 8,147 $ 6.97 3.94 $ 94,712 Exercisable at December 31, 2016 6,962 $ 5.37 3.24 $ 85,916 (1) The expected to vest options are the result of applying pre-vesting forfeiture rate assumptions to unvested options outstanding.
Summary of RSU Activity	The following table summarizes the activity related to the Company’s RSUs for the year ended December 31, 2016. 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 Weighted- Average Grant- Date Fair Value Shares Per Share Unvested and outstanding at December 31, 2015 43,170 $ 32.46 Granted 51,231 $ 16.15 Vested (26,918 ) $ 23.70 Canceled (19,414 ) $ 25.88 Unvested and outstanding at December 31, 2016 48,069 $ 22.64
Compensation Expense Allocated	Stock-based compensation expense is allocated based on the cost center to which the award holder belongs. Total stock-based compensation expense by function for the years ended December 31, 2016, 2015 and 2014 is as follows (in thousands): Year Ended December 31, 2016 2015 2014 Cost of revenue $ 29,502 $ 40,705 $ 50,536 Research and development 335,498 401,537 360,726 Sales and marketing 160,935 156,904 157,263 General and administrative 89,298 82,972 63,072 Total stock-based compensation expense $ 615,233 $ 682,118 $ 631,597

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Summary of Domestic and Foreign Components of Pre-Tax Loss	The domestic and foreign components of pre-tax loss for the years ended December 31, 2016, 2015 and 2014 are as follows (in thousands): Year Ended December 31, 2016 2015 2014 Domestic $ (237,325 ) $ (201,628 ) $ (164,854 ) Foreign (203,509 ) (331,677 ) (413,497 ) Loss before income taxes $ (440,834 ) $ (533,305 ) $ (578,351 )
Components of Provision (Benefit) for Income Taxes	The components of the provision (benefit) for income taxes for the years ended December 31, 2016, 2015 and 2014 are as follows (in thousands): Year Ended December 31, 2016 2015 2014 Current: Federal $ 1,087 $ — $ — State (143 ) 1,226 720 Foreign 19,870 14,625 8,358 Total current provision for income taxes 20,814 15,851 9,078 Deferred: Federal 293 (23,208 ) (8,972 ) State 17 (852 ) (128 ) Foreign (5,085 ) (4,065 ) (509 ) Total deferred benefit for income taxes (4,775 ) (28,125 ) (9,609 ) Provision (benefit) for income taxes $ 16,039 $ (12,274 ) $ (531 )
Schedule of Reconciliation of Statutory Federal Income Tax Rate to Effective Tax Rate	The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2016, 2015 and 2014: Year Ended December 31, 2016 2015 2014 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 0.0 (0.1 ) (0.1 ) Stock-based compensation (2.3 ) (2.9 ) (4.2 ) Research and development credits 6.6 7.2 25.2 Valuation Allowance (7.0 ) 3.1 (9.4 ) Nondeductible expenses (7.0 ) (5.6 ) (4.5 ) Foreign rate differential (19.5 ) (23.7 ) (26.4 ) Change in tax positions (9.5 ) (10.7 ) (15.9 ) Other 0.1 0.0 0.4 Effective tax rate (3.6 )% 2.3 % 0.1 %
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, 2016 and 2015 are as follows (in thousands): December 31, 2016 2015 Deferred tax assets: Net operating loss carryforwards $ 235,668 $ 242,987 Accruals and reserves 61,594 36,133 Stock-based compensation expense 64,136 80,106 Research and development credits 251,808 209,425 California Enterprise Zone Credit 12,266 11,710 Fixed assets and intangible assets 2,631 1,457 Other 11,980 7,059 Total deferred tax assets 640,083 588,877 Valuation allowance (439,993 ) (378,448 ) Total deferred tax assets, net of valuation allowance 200,090 210,429 Deferred tax liabilities: Fixed assets and intangible assets (168,223 ) (174,007 ) Convertible notes (24,303 ) (30,002 ) Other (1,612 ) (1,577 ) Total deferred tax liabilities (194,138 ) (205,586 ) Net deferred tax assets $ 5,952 $ 4,843
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, 2016 2015 2014 Balance at the beginning of the year $ 209,443 $ 182,484 $ 43,061 Additions related to prior year tax positions 3,682 1,820 — Reductions related to prior year tax positions — (45,305 ) (50 ) Additions related to current year tax positions 56,383 70,444 139,473 Balance at the end of the year $ 269,508 $ 209,443 $ 182,484
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, 2016 2015 Total unrecognized tax benefits balance $ 269,508 $ 209,443 Amounts netted against related deferred tax assets (263,696 ) (208,307 ) Unrecognized tax benefits recorded on consolidated balance sheets $ 5,812 $ 1,136

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Minimum Commitments and Sublease Income Under Non-Cancelable Capital and Operating Lease Agreements	A summary of gross lease commitments and sublease income as of December 31, 2016 is as follows (in thousands): Operating Sublease Capital Leases Income Leases Years ending December 31, 2017 $ 156,757 $ (24,101 ) $ 85,886 2018 148,157 (23,712 ) 45,984 2019 116,189 (16,577 ) 21,062 2020 90,664 (9,038 ) — 2021 57,937 (8,969 ) — Thereafter 163,315 — — $ 733,019 $ (82,397 ) 152,932 Less: Amounts representing interest 5,247 Total capital lease obligation 147,685 Less: Short-term portion 80,848 Long-term portion $ 66,837

Segment Information and Opera39

Segment Information and Operations by Geographic Area (Tables)	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Revenue by Geography	Revenue by geography is based on the billing addresses of the customers. The following tables set forth revenue by services and revenue by geographic area (in thousands): Year Ended December 31, 2016 2015 2014 Revenue by services: Advertising services $ 2,248,052 $ 1,994,036 $ 1,255,688 Data licensing and other 281,567 223,996 147,314 Total revenue $ 2,529,619 $ 2,218,032 $ 1,403,002 Year Ended December 31, 2016 2015 2014 Revenue by geographic area: United States $ 1,564,776 $ 1,443,240 $ 945,720 International 964,843 774,792 457,282 Total revenue $ 2,529,619 $ 2,218,032 $ 1,403,002
Property and Equipment Net by Geographic Area	The following table sets forth property and equipment, net by geographic area (in thousands): December 31, December 31, 2016 2015 Property and equipment, net: United States $ 728,429 $ 683,176 International 55,472 52,123 Total property and equipment, net $ 783,901 $ 735,299

Restructuring Charges (Tables)

Restructuring Charges (Tables)	12 Months Ended
	Dec. 31, 2016
Restructuring And Related Activities [Abstract]
Summary of Restructuring Charges and Related Liabilities	The following table summarizes the restructuring charges for the year ended December 31, 2016 and related liabilities as of December 31, 2016 (in thousands): 2016 Employee 2016 Termination Plan Lease Plan Charges $ 21,611 $ 79,685 Cash payment (11,629 ) (3,562 ) Non-cash and other adjustments (6,357 ) (19,577 ) Accrued as of December 31, 2016 $ 3,625 $ 56,546 Cost of revenue $ 13 $ 49,006 Research and development 4,246 11,693 Sales and marketing 17,310 13,072 General and administrative 42 5,914 Total costs incurred in 2016 $ 21,611 $ 79,685 Reflected in consolidated balance sheets: (1) Accrued and other current liabilities $ 3,625 $ 52,317 Other long-term liabilities $ — $ 4,229 (1)

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Accounting Policies [Line Items]
Capital lease obligations included in short-term and long-term	$ 147,700,000	$ 147,900,000
Interest expense in relation to capital lease arrangements.	5,500,000	8,800,000	$ 10,200,000
Interest earned on cash, cash equivalent and marketable securities	24,300,000	9,100,000	1,900,000
Capitalized interest expenses	4,300,000	5,000,000	0
Impairment charges on goodwill	0
Impairment charges on intangible assets	0
Software developing program costs capitalized	$ 139,000,000	92,800,000	79,500,000
Percent likelihood for tax benefit amounts to be realized upon settlement	50.00%
Advertising expense	$ 114,300,000	119,700,000	46,600,000
Cost of Revenue
Significant Accounting Policies [Line Items]
Amortization of capitalized costs	74,600,000	37,800,000	15,200,000
Internal Use Software and Website Development Costs
Significant Accounting Policies [Line Items]
Share-based compensation, capitalized amount	$ 73,900,000	$ 50,300,000	$ 40,800,000
Customer Concentration Risk | Accounts Receivable
Significant Accounting Policies [Line Items]
Concentration risk percentage	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	$ 9,400,000	$ 3,000,000
Other assets
Significant Accounting Policies [Line Items]
Restricted Cash Balances	$ 29,600,000	$ 31,100,000
Maximum
Significant Accounting Policies [Line Items]
Capital leases term	4 years
Intangible assets, estimated useful lives	11 years
Maximum | Internal Use Software and Website Development Costs
Significant Accounting Policies [Line Items]
Estimated Useful Life	4 years
Minimum
Significant Accounting Policies [Line Items]
Capital leases term	3 years
Minimum | Internal Use Software and Website Development Costs
Significant Accounting Policies [Line Items]
Estimated Useful Life	1 year
Employee Stock Options
Significant Accounting Policies [Line Items]
Stock-based compensation expense, dividend yield	0.00%
Performance Condition Awards
Significant Accounting Policies [Line Items]
Vesting condition period	1 year
Service Condition Awards
Significant Accounting Policies [Line Items]
Vesting condition period	4 years

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2016
Computer Hardware, Networking Equipment and Office Equipment | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life	3 years
Computer Hardware, Networking Equipment and Office Equipment | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life	5 years
Computer Software | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life	1 year
Computer Software | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life	4 years
Furniture and Fixtures | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated Useful Life	Lesser of estimated useful life or remaining lease term

Cash, Cash Equivalents and Sh43

Cash, Cash Equivalents and Short-term Investments - Cash, Cash and Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash and cash equivalents:
Cash	$ 253,808	$ 300,363
Cash and cash equivalents	988,598	911,471	$ 1,510,724	$ 841,010
Short-term investments:
Short-term investments	2,785,981	2,583,877
Money Market Funds
Cash and cash equivalents:
Cash and cash equivalents	422,515	141,700
U.S. Government and Agency Securities Including Treasury Bills
Cash and cash equivalents:
Cash and cash equivalents	12,639
Short-term investments:
Short-term investments	1,183,768	1,156,418
Corporate Notes, Commercial Paper and Certificates of Deposit
Cash and cash equivalents:
Cash and cash equivalents	299,636	469,408
Short-term investments:
Short-term investments	$ 1,602,213	$ 1,427,459

Cash, Cash Equivalents and Sh44

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, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Gross Amortized Costs	$ 2,788,322	$ 2,587,853
Gross Unrealized Gains	250	27
Gross Unrealized Losses	(2,591)	(4,003)
Aggregated Estimated Fair Value	2,785,981	2,583,877
U.S. Government and Agency Securities Including Treasury Bills
Schedule Of Available For Sale Securities [Line Items]
Gross Amortized Costs	1,185,274	1,158,479
Gross Unrealized Gains	136	6
Gross Unrealized Losses	(1,642)	(2,067)
Aggregated Estimated Fair Value	1,183,768	1,156,418
Corporate Notes, Commercial Paper and Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Gross Amortized Costs	1,603,048	1,429,374
Gross Unrealized Gains	114	21
Gross Unrealized Losses	(949)	(1,936)
Aggregated Estimated Fair Value	$ 1,602,213	$ 1,427,459

Cash, Cash Equivalents and Sh45

Cash, Cash Equivalents and Short-term Investments - Contractual Maturities of Securities Classified as Available-for-Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Cash And Cash Equivalents And Marketable Securities [Abstract]
Due within one year	$ 1,990,083
Due after one year through two years	795,898
Total	$ 2,785,981	$ 2,583,877

Cash, Cash Equivalents and Sh46

Cash, Cash Equivalents and Short-term Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Securities continuous loss position for 12 months or longer		$ 0
Impairment loss on securities	$ 0	$ 0

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, 2016	Dec. 31, 2015
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	$ 2,785,981	$ 2,583,877
Other current assets	1,955	6,804
Other current liabilities	500	3,005
Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Total	3,522,726	3,201,789
Total	500	3,005
Fair Value, Measurements, Recurring | Agency Securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	526,266	589,297
Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	422,515	141,700
Fair Value, Measurements, Recurring | Treasury Bills
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	12,639
Short-term investments		29,953
Fair Value, Measurements, Recurring | Corporate Notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	7,387
Short-term investments	689,986	693,593
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	292,249	419,110
Short-term investments	311,238	229,965
Fair Value, Measurements, Recurring | US Government Securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	657,502	537,168
Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		50,298
Short-term investments	600,989	503,901
Fair Value, Measurements, Recurring | Foreign currency contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	1,955	6,804
Other current liabilities	500	3,005
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Total	435,154	171,653
Level 1 | Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	422,515	141,700
Level 1 | Fair Value, Measurements, Recurring | Treasury Bills
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	12,639
Short-term investments		29,953
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Total	3,087,572	3,030,136
Total	500	3,005
Level 2 | Fair Value, Measurements, Recurring | Agency Securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	526,266	589,297
Level 2 | Fair Value, Measurements, Recurring | Corporate Notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	7,387
Short-term investments	689,986	693,593
Level 2 | Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	292,249	419,110
Short-term investments	311,238	229,965
Level 2 | Fair Value, Measurements, Recurring | US Government Securities
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	657,502	537,168
Level 2 | Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		50,298
Short-term investments	600,989	503,901
Level 2 | Fair Value, Measurements, Recurring | Foreign currency contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	1,955	6,804
Other current liabilities	$ 500	$ 3,005

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Notional principal of foreign currency contracts outstanding	$ 536,900	$ 522,400
Net gain (losses) on foreign currency contracts	1,600	400
Convertible Notes | Senior Notes Due 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 935,000	935,000	$ 935,000	$ 900,000
Debt Instrument, percentage	0.25%		0.25%
Debt Instrument, due date	2,019
Convertible Notes | Senior Notes Due 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 954,000	$ 954,000	$ 954,000	$ 900,000
Debt Instrument, percentage	1.00%		1.00%
Debt Instrument, due date	2,021
Level 2 | Convertible Notes | Senior Notes Due 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of notes based on a market approach	$ 879,000
Level 2 | Convertible Notes | Senior Notes Due 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of notes based on a market approach	$ 880,400

Fair Value Measurements - Sch49

Fair Value Measurements - Schedule of Fair Values of Outstanding Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets
Foreign currency contracts not designated as hedging instruments	$ 1,955	$ 6,804
Liabilities
Foreign currency contracts not designated as hedging instruments	500	3,005
Total fair value of derivative instruments	$ 1,455	$ 3,799

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property and equipment, net
Property and equipment, gross	$ 1,641,828	$ 1,314,009
Less: Accumulated depreciation and amortization	(857,927)	(578,710)
Property and equipment, net	783,901	735,299
Equipment
Property and equipment, net
Property and equipment, gross	909,797	720,421
Furniture and Leasehold Improvements
Property and equipment, net
Property and equipment, gross	304,613	297,274
Capitalized Software
Property and equipment, net
Property and equipment, gross	353,163	211,241
Construction in Progress
Property and equipment, net
Property and equipment, gross	$ 74,255	$ 85,073

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Depreciation expense	$ 332.8	$ 257.2	$ 171.6
Computer Hardware, Networking Equipment and Office Equipment
Property Plant And Equipment [Line Items]
Gross carrying amount of property and equipment	361.1	370.3
Accumulated depreciation of the equipment	207	226.9
Depreciation expense	$ 100.8	$ 118.7	$ 108.7

Goodwill and Intangible Asset52

Goodwill and Intangible Assets - Schedule of Goodwill Activities (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill
Beginning balance		$ 1,122,728	$ 622,570
Acquisitions		74,186
Foreign currency translation adjustment		(11,599)	(1,029)
Ending balance		1,185,315	1,122,728	$ 622,570
TellApart Inc
Goodwill
Acquisitions	$ 395,000		394,989
Other acquisitions
Goodwill
Acquisitions		$ 74,200	$ 106,198	$ 155,100

Goodwill and Intangible Asset53

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite Lived Intangible Assets [Line Items]
Impairment charges on goodwill	$ 0
Amortization of intangible assets	69,300,000	$ 54,700,000	$ 36,600,000
Fully amortized finite lived intangible assets	$ 59,500,000
Maximum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	11 years
Patents and Developed Technologies | Maximum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	11 years
Publisher and Advertiser Relationships | Minimum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	2 years
Publisher and Advertiser Relationships | Maximum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	5 years
Assembled Workforce and Other Intangible Assets | Minimum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	1 year
Assembled Workforce and Other Intangible Assets | Maximum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	4 years

Goodwill and Intangible Asset54

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 175,711	$ 211,804
Accumulated Amortization	(80,377)	(70,789)
Net Carrying Value	95,334	141,015
Patents and Developed Technologies
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	122,611	132,444
Accumulated Amortization	(47,160)	(43,991)
Net Carrying Value	75,451	88,453
Publisher and Advertiser Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	53,100	75,300
Accumulated Amortization	(33,217)	(23,803)
Net Carrying Value	$ 19,883	51,497
Assembled Workforce
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value		1,960
Accumulated Amortization		(1,714)
Net Carrying Value		246
Other Intangible Assets
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value		2,100
Accumulated Amortization		(1,281)
Net Carrying Value		$ 819

Goodwill and Intangible Asset55

Goodwill and Intangible Assets - Schedule of Estimated Future Amortization Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
2,017	$ 43,810
2,018	18,855
2,019	8,796
2,020	6,523
2,021	6,126
Thereafter	11,224
Net Carrying Value	$ 95,334	$ 141,015

Accrued and Other Current Lia56

Accrued and Other Current Liabilities - Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued compensation	$ 82,354	$ 90,906
Accrued restructuring	55,942	396
Accrued publisher, content and ad network costs	44,362	23,486
Deferred revenue	33,659	23,674
Accrued tax liabilities	29,558	25,880
Accrued sales and marketing expenses	22,431	27,948
Accrued other	112,631	91,502
Total	$ 380,937	$ 283,792

Acquisitions and Other Invest57

Acquisitions and Other Investments -2016 Acquisitions - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill acquired	$ 74,186
Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives	11 years
Other acquisitions
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 91,400	$ 118,900	$ 188,100
Business acquisition, common stock issued	1,300	60,100	121,200
Business acquisition, purchase price cash consideration	90,100	58,800	66,900
Net cash acquired	5,000
Acquisition purchase price allocated to assets	200	3,200	6,500
Acquisition purchase price allocated to deferred tax liability	2,400	3,400	3,200
Goodwill acquired	74,200	106,198	155,100
Business acquisition, goodwill expected tax deductible amount	63,800	4,100	21,900
Other acquisitions | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	$ 14,400	$ 12,900	$ 28,100
Other acquisitions | Developed Technology Rights | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives	24 months	60 months	48 months

Acquisitions and Other Invest58

Acquisitions and Other Investments -2015 Acquisitions - Additional Information (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	May 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill acquired		$ 74,186
Fair value of contingent payment			$ 102,900	$ 97,700
Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives		11 years
TellApart Inc
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration	$ 22,600
Business acquisition, common stock issued	12.2
Business acquisition, assumed common shares / stock options	1.2
Business Combination, Consideration Transferred	$ 479,100
Business acquisition, common stock issued	456,500
Acquisition purchase price allocated to cash	29,600
Account receivables	19,700
Other tangible assets	2,200
Acquisition purchase price allocated to liability	11,800
Acquisition purchase price allocated to deferred tax liability	22,400
Goodwill acquired	395,000		$ 394,989
TellApart Inc | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	21,400
TellApart Inc | Developed Technology Rights | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			12 months
TellApart Inc | Developed Technology Rights | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			72 months
TellApart Inc | Advertiser Relationships
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	43,300
TellApart Inc | Advertiser Relationships | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			12 months
TellApart Inc | Advertiser Relationships | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			72 months
TellApart Inc | Trade Name
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	$ 2,100
TellApart Inc | Trade Name | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			12 months
TellApart Inc | Trade Name | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			72 months
TellApart Inc | Stock Options
Business Acquisition [Line Items]
Business acquisition, assumed common shares / stock options	1.3
Other acquisitions
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration		$ 90,100	$ 58,800	66,900
Business Combination, Consideration Transferred		91,400	118,900	188,100
Business acquisition, common stock issued		1,300	60,100	121,200
Acquisition purchase price allocated to cash		5,000
Acquisition purchase price allocated to deferred tax liability		2,400	3,400	3,200
Goodwill acquired		74,200	106,198	155,100
Acquisition purchase price allocated to assets		200	3,200	6,500
Business acquisition, goodwill expected tax deductible amount		63,800	4,100	21,900
Other acquisitions | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets		$ 14,400	$ 12,900	$ 28,100
Other acquisitions | Developed Technology Rights | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			12 months	12 months
Other acquisitions | Developed Technology Rights | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives		24 months	60 months	48 months
All Acquisitions
Business Acquisition [Line Items]
Equity compensation service period			48 months
All Acquisitions | Employee Stock Options
Business Acquisition [Line Items]
Equity compensation service period			45 months	48 months
Unrecognized share-based compensation expense			$ 37,200

Acquisitions and Other Invest59

Acquisitions and Other Investments -2014 Acquisitions - Additional Information (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	May 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill acquired		$ 74,186
Fair value of contingent payment			$ 102,900	$ 97,700
Unrecognized share-based compensation expense		$ 844,000
Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives		11 years
Gnip Inc
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration	$ 107,300
Business acquisition, common stock issued	0.6
Business acquisition, assumed common shares / stock options	0.4
Business Combination, Consideration Transferred	$ 134,100
Acquisition purchase price allocated to liability	5,800
Acquisition purchase price allocated to deferred tax liability	6,400
Goodwill acquired	104,700
Acquisition purchase price allocated to assets	9,100
Gnip Inc | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	23,200
Intangible assets, estimated useful lives				60 months
Gnip Inc | Customer Relationships
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets	$ 9,300
Intangible assets, estimated useful lives				60 months
Other acquisitions
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration		$ 90,100	58,800	$ 66,900
Business Combination, Consideration Transferred		91,400	118,900	188,100
Acquisition purchase price allocated to deferred tax liability		2,400	3,400	3,200
Goodwill acquired		74,200	106,198	155,100
Acquisition purchase price allocated to assets		200	3,200	6,500
Business acquisition, common stock issued		1,300	60,100	121,200
Business acquisition, goodwill expected tax deductible amount		63,800	4,100	21,900
Other acquisitions | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets		$ 14,400	$ 12,900	$ 28,100
Other acquisitions | Developed Technology Rights | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives			12 months	12 months
Other acquisitions | Developed Technology Rights | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives		24 months	60 months	48 months
Other acquisitions | Customer Relationships
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets				$ 1,600
Other acquisitions | Customer Relationships | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				12 months
Other acquisitions | Customer Relationships | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				48 months
All Acquisitions
Business Acquisition [Line Items]
Equity compensation service period			48 months
All Acquisitions | Employee Stock Options
Business Acquisition [Line Items]
Equity compensation service period			45 months	48 months
Unrecognized share-based compensation expense				$ 16,900

Acquisitions and Other Invest60

Acquisitions and Other Investments - Investments in Privately-Held Companies - Additional Information (Details) - USD ($) $ in Millions	Dec. 30, 2016	Dec. 30, 2015
Schedule Of Investments [Abstract]
Cost method investments	$ 90.2	$ 14.2

Convertible Notes - Additional

Convertible Notes - Additional Information (Details) $ / shares in Units, shares in Millions		1 Months Ended	12 Months Ended
		Oct. 31, 2014USD ($)	Dec. 31, 2016USD ($)d$ / shares	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)$ / sharesshares	Sep. 30, 2014USD ($)
Debt Instrument [Line Items]
Conversion Price | $ / shares			$ 77.64
Amortization of discount on convertible notes			$ 74,660,000	$ 69,185,000	$ 18,823,000
Convertible notes			$ 1,538,967,000	1,455,095,000
Purchases of convertible note hedges					407,169,000
Exercise price of the warrants | $ / shares			$ 105.28
Proceeds from issuance of warrants					289,272,000
Convertible Notes
Debt Instrument [Line Items]
Initial purchasers' discount					28,300,000
Debt issuance costs					500,000
Proceeds from offerings, net of transaction costs					1,860,000,000
Debt Instrument, frequency of periodic payment			semi-annually
Debt Instrument, date of first required payment			Mar. 15, 2015
Debt Instrument Payment Terms			The interest rates are fixed at 0.25% and 1.00% per annum and are payable semi-annually in arrears on March 15 and September 15 of each year, commencing on March 15, 2015.
Amortization of debt discount allocated to interest expense			$ 4,900,000	5,100,000	1,400,000
Coupon interest expense			$ 11,900,000	11,900,000	3,300,000
Price percentage for repurchase of notes if repurchase option is elected			100.00%
Equity component of the convertible note issuance, net					100,000
Amortization of discount on convertible notes					$ 400,000
Number of shares authorized for repurchase under hedge agreement | shares					24.3
Exercise price of the option to repurchase stock | $ / shares					$ 77.64
Purchases of convertible note hedges					$ 407,200,000
Number of warrants issued | shares					24.3
Exercise price of the warrants | $ / shares					$ 105.28
Proceeds from issuance of warrants					$ 289,300,000
Convertible Notes | Interest Expense
Debt Instrument [Line Items]
Amortization of discount on convertible notes			$ 79,000,000	74,200,000	18,800,000
Convertible Notes | Scenario One
Debt Instrument [Line Items]
Convertible debt instrument, consecutive trading days threshold			30 days
Convertible debt instrument, percentage of conversion price to trigger conversion to common stock			130.00%
Convertible Notes | Scenario One | Minimum
Debt Instrument [Line Items]
Convertible debt instrument, trading days threshold | d			20
Convertible Notes | Scenario Two
Debt Instrument [Line Items]
Convertible debt instrument, trading days threshold | d			5
Convertible debt instrument, consecutive trading days threshold			5 days
Convertible debt instrument, percentage of conversion price to trigger conversion to common stock			98.00%
Convertible Notes | Common Stock
Debt Instrument [Line Items]
Debt instrument, conversion principal amount			$ 1,000
Debt Instrument, conversion ratio			12.8793
Conversion Price | $ / shares			$ 77.64
Debt Instrument, terms of conversion			Each $1,000 of principal of these Notes will initially be convertible into 12.8793 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $77.64 per share, subject to adjustment upon the occurrence of specified events.
Convertible Notes | Senior Notes Due 2019
Debt Instrument [Line Items]
Debt instrument, principal amount			$ 935,000,000	935,000,000	$ 935,000,000	$ 900,000,000
Proceeds from Issuance of Debt		$ 35,000,000
Initial purchasers' discount	[1]		$ 136,376,000	181,994,000
Debt Instrument, percentage			0.25%		0.25%
Debt Instrument, conversion earliest date			Mar. 15, 2019
Carrying amount of the equity component	[2]		$ 222,826,000	222,826,000
Effective interest rate for amortization to interest expense			5.75%
Convertible notes			$ 798,624,000	753,006,000
Remaining period for convertible debt			32 months
Convertible Notes | Senior Notes Due 2021
Debt Instrument [Line Items]
Debt instrument, principal amount			$ 954,000,000	954,000,000	$ 954,000,000	$ 900,000,000
Proceeds from Issuance of Debt		$ 54,000,000
Initial purchasers' discount	[1]		$ 213,657,000	251,911,000
Debt Instrument, percentage			1.00%		1.00%
Debt Instrument, conversion earliest date			Mar. 15, 2021
Carrying amount of the equity component	[2]		$ 283,283,000	283,283,000
Effective interest rate for amortization to interest expense			6.25%
Convertible notes			$ 740,343,000	$ 702,089,000
Remaining period for convertible debt			56 months
[1]	Included in the consolidated balance sheets within convertible notes and amortized over the remaining lives of the Notes.
[2]	Included in the consolidated balance sheets within additional paid-in capital.

Convertible Notes - Components

Convertible Notes - Components of Notes (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2014
Principal amounts:
Net carrying amount		$ 1,538,967	$ 1,455,095
Convertible Notes
Principal amounts:
Unamortized initial purchasers' discount and debt discount				$ (28,300)
Convertible Notes | Senior Notes Due 2019
Principal amounts:
Debt instrument, principal amount		935,000	935,000	935,000	$ 900,000
Unamortized initial purchasers' discount and debt discount	[1]	(136,376)	(181,994)
Net carrying amount		798,624	753,006
Carrying amount of the equity component	[2]	222,826	222,826
Convertible Notes | Senior Notes Due 2021
Principal amounts:
Debt instrument, principal amount		954,000	954,000	$ 954,000	$ 900,000
Unamortized initial purchasers' discount and debt discount	[1]	(213,657)	(251,911)
Net carrying amount		740,343	702,089
Carrying amount of the equity component	[2]	$ 283,283	$ 283,283
[1]	Included in the consolidated balance sheets within convertible notes and amortized over the remaining lives of the Notes.
[2]	Included in the consolidated balance sheets within additional paid-in capital.

Net Loss Per Share - Basic and

Net 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, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net loss	$ (456,873)	$ (521,031)	$ (577,820)
Basic shares:
Weighted-average common shares outstanding	708,010	670,132	613,944
Weighted-average restricted stock subject to repurchase	(5,875)	(7,708)	(8,954)
Weighted-average shares used to compute basic net loss per share	702,135	662,424	604,990
Diluted shares:
Weighted-average shares used to compute diluted net loss per share	702,135	662,424	604,990
Net loss per share attributable to common stockholders:
Basic	$ (0.65)	$ (0.79)	$ (0.96)
Diluted	$ (0.65)	$ (0.79)	$ (0.96)

Net Loss Per Share - Summary of

Net 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, 2016	Dec. 31, 2015	Dec. 31, 2014
RSUs
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	48,069	43,170	64,135
Warrants
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	24,329	24,329	24,329
Stock Options
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	8,723	11,177	20,420
Restricted Common Stock and Others
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	6,637	9,146	9,335

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Earnings Per Share [Abstract]
Conversion Price	$ 77.64
Conversion spread will have a dilutive impact on diluted net income per share of common stock | shares	24,300,000
Exercise price of the warrants	$ 105.28

Preferred Stock - Additional In

Preferred Stock - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Features Of Convertible Preferred Stock [Abstract]
Convertible preferred stock terms of conversion	Each share of preferred stock was convertible to one share of common stock. Upon the closing of the Company’s initial public offering on November 13, 2013
Preferred stock, shares authorized	200,000,000	200,000,000
Preferred stock, shares outstanding	0	0

Common Stock and Stockholders67

Common Stock and Stockholders' Equity - Additional Information (Details) - USD ($)	Nov. 07, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	May 25, 2016	Oct. 22, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized		5,000,000,000	5,000,000,000
Common stock, par value		$ 0.000005	$ 0.000005
Voting rights		Each share of common stock is entitled to one vote
Dividends declared		$ 0
Options granted expire years		10 years
Issuance of common stock upon purchases under employee stock purchase plan, shares		2,000,000	1,500,000
Employee stock purchase plan (ESOP), weighted average purchase price of shares purchased		$ 11.98	$ 25.78
Incremental Share-based compensation cost		$ 0	$ 0	$ 32,600,000
Unamortized stock-based compensation expense related to unvested awards		$ 844,000,000
Unrecognized share-based compensation expense, weighted average recognition period		2 years 2 months 5 days
Internal Use Software and Website Development Costs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, capitalized amount		$ 73,900,000	$ 50,300,000	40,800,000
Jack Dorsey Trust
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares given back and contributed by Chief Executive Officer						6,814,085
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 and restricted stock units outstanding		46,300,000
Common stock, reserved for future issuance		123,000,000
2007 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options and restricted stock units outstanding		9,100,000
Shares issued during the period		0
2016 Equity Incentive Plan | Jack Dorsey Trust
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares given back and contributed by Chief Executive Officer					6,814,085
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%
All Acquisitions
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period			48 months
Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, granted		3,320,000
Weighted Average Grant Date Fair Value Per Share, Granted		$ 16.63
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options exercised, intrinsic value		$ 41,400,000	$ 337,200,000	$ 872,800,000
Employee Stock Options | All Acquisitions
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period			45 months	48 months
Unamortized stock-based compensation expense related to unvested awards				$ 16,900,000
PRSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period		1 year
Percentage of shares ultimately vest form annual target amount		70.00%
Number of Shares, granted		165,833
Shares granted at target level		100.00%
Weighted Average Grant Date Fair Value Per Share, Granted		$ 17.90
Additional number of shares, granted		1,687,833
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, granted		51,231,000
Weighted Average Grant Date Fair Value Per Share, Granted		$ 16.15
Fair value of restricted stock units vested		$ 466,400,000	$ 849,800,000
Maximum | 2016 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares initially reserved					6,814,085
Maximum | Restricted Common Stock | All Acquisitions
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period		4 years

Common Stock and Stockholders68

Common Stock and Stockholders' Equity - Summary of Restricted Stock Activity (Details) - Restricted Common Stock shares in Thousands	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Unvested Shares, beginning of period | shares	4,540
Number of Shares, granted | shares	3,320
Number of Shares, vested | shares	(2,371)
Number of Shares, Canceled | shares	(392)
Number of Unvested Shares, end of period | shares	5,097
Weighted Average Grant Date Fair Value Per Share, beginning of period | $ / shares	$ 33.88
Weighted Average Grant Date Fair Value Per Share, Granted | $ / shares	16.63
Weighted Average Grant Date Fair Value Per Share, Vested | $ / shares	32.94
Weighted Average Grant Date Fair Value Per Share, Canceled | $ / shares	34.46
Weighted Average Grant Date Fair Value Per Share, end of period | $ / shares	$ 23.04

Common Stock and Stockholders69

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, 2016	Dec. 31, 2015
Options Outstanding - Number of Shares
Outstanding at beginning of period	11,177
Options granted and assumed in connection with acquisitions	557
Options exercised	(2,864)
Options canceled	(147)
Outstanding at end of period	8,723	11,177
Vested and expected to vest at end of period	8,147
Exercisable at end of period	6,962
Options Outstanding - Weighted-Average Exercise Price Per Share
Outstanding at beginning of period	$ 6.55
Options granted and assumed in connection with acquisitions	3.23
Options exercised	2.56
Options canceled	3.50
Outstanding at end of period	7.71	$ 6.55
Vested and expected to vest at end of period	6.97
Exercisable at end of period	$ 5.37
Options Outstanding - Weighted-Average Remaining Contractual Life
Outstanding	4 years 3 months	5 years 10 months 10 days
Vested and expected to vest at end of period	3 years 11 months 9 days
Exercisable at end of period	3 years 2 months 27 days
Options Outstanding - Aggregate Intrinsic Value
Outstanding	$ 98,240	$ 199,576
Vested and expected to vest at end of period	94,712
Exercisable at end of period	$ 85,916

Common Stock and Stockholders70

Common Stock and Stockholders' Equity - Summary of RSU Activity (Details) - RSUs shares in Thousands	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Unvested Shares, beginning of period | shares	43,170
Number of Shares, granted | shares	51,231
Number of Shares, vested | shares	(26,918)
Number of Shares, Canceled | shares	(19,414)
Number of Unvested Shares, end of period | shares	48,069
Weighted Average Grant Date Fair Value Per Share, beginning of period | $ / shares	$ 32.46
Weighted Average Grant Date Fair Value Per Share, Granted | $ / shares	16.15
Weighted Average Grant Date Fair Value Per Share, Vested | $ / shares	23.70
Weighted Average Grant Date Fair Value Per Share, Canceled | $ / shares	25.88
Weighted Average Grant Date Fair Value Per Share, end of period | $ / shares	$ 22.64

Common Stock and Stockholders71

Common Stock and Stockholders' Equity - Compensation Expense Allocated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 615,233	$ 682,118	$ 631,597
Cost of Revenue
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	29,502	40,705	50,536
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	335,498	401,537	360,726
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	160,935	156,904	157,263
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 89,298	$ 82,972	$ 63,072

Income Taxes - Summary of Domes

Income Taxes - Summary of Domestic and Foreign Components of Pre-Tax Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ (237,325)	$ (201,628)	$ (164,854)
Foreign	(203,509)	(331,677)	(413,497)
Loss before income taxes	$ (440,834)	$ (533,305)	$ (578,351)

Income Taxes - Components of Pr

Income Taxes - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ 1,087
State	(143)	$ 1,226	$ 720
Foreign	19,870	14,625	8,358
Total current provision for income taxes	20,814	15,851	9,078
Deferred:
Federal	293	(23,208)	(8,972)
State	17	(852)	(128)
Foreign	(5,085)	(4,065)	(509)
Total deferred benefit for income taxes	(4,775)	(28,125)	(9,609)
Provision (benefit) for income taxes	$ 16,039	$ (12,274)	$ (531)

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Statutory Federal Income Tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Tax at federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	0.00%	(0.10%)	(0.10%)
Stock-based compensation	(2.30%)	(2.90%)	(4.20%)
Research and development credits	6.60%	7.20%	25.20%
Valuation Allowance	(7.00%)	3.10%	(9.40%)
Nondeductible expenses	(7.00%)	(5.60%)	(4.50%)
Foreign rate differential	(19.50%)	(23.70%)	(26.40%)
Change in tax positions	(9.50%)	(10.70%)	(15.90%)
Other	0.10%	0.00%	0.40%
Effective tax rate	(3.60%)	2.30%	0.10%

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, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carryforwards	$ 235,668	$ 242,987
Accruals and reserves	61,594	36,133
Stock-based compensation expense	64,136	80,106
Research and development credits	251,808	209,425
California Enterprise Zone Credit	12,266	11,710
Fixed assets and intangible assets	2,631	1,457
Other	11,980	7,059
Total deferred tax assets	640,083	588,877
Valuation allowance	(439,993)	(378,448)
Total deferred tax assets, net of valuation allowance	200,090	210,429
Deferred tax liabilities:
Fixed assets and intangible assets	(168,223)	(174,007)
Convertible notes	(24,303)	(30,002)
Other	(1,612)	(1,577)
Total deferred tax liabilities	(194,138)	(205,586)
Net deferred tax assets	$ 5,952	$ 4,843

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Deferred tax assets	$ 5,952,000	$ 4,843,000
Undistributed earnings for foreign subsidiaries	157,100,000
Operating loss carryforwards related to excess tax benefit from stock-based compensation	3,420,000,000
Income tax benefits resulting from stock awards that were credited to stockholders' equity	200,000
Unrecognized tax benefits	269,508,000	209,443,000	$ 182,484,000	$ 43,061,000
Unrecognized tax benefits, if recognized would not affect the annual effective tax rate	263,700,000
Unrecognized tax benefits, if recognized would affect the annual effective tax rate	5,800,000
Net unrecognized tax benefit included in the deferred and other long-term tax liabilities	5,812,000	$ 1,136,000
California Enterprise Zone
Income Tax [Line Items]
Credit carryforwards amount	$ 18,900,000
Credit carryforward, expiration year	2,023
Uncertain Tax Positions
Income Tax [Line Items]
Significant accrued interest and penalties related to uncertain tax positions	$ 0
Foreign Jurisdictions
Income Tax [Line Items]
Deferred tax assets	6,600,000
Federal
Income Tax [Line Items]
Net operating loss carryforwards	$ 3,470,000,000
Operating loss carryforwards, expiration year	2,027
Credit carryforward, expiration start year	2,027
Federal | Research
Income Tax [Line Items]
Credit carryforwards amount	$ 222,800,000
State
Income Tax [Line Items]
Net operating loss carryforwards	$ 1,410,000,000
Operating loss carryforwards, expiration year	2,017
State | Research
Income Tax [Line Items]
Credit carryforwards amount	$ 184,500,000

Income Taxes - Schedule of Re77

Income Taxes - Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Balance at the beginning of the year	$ 209,443	$ 182,484	$ 43,061
Additions related to prior year tax positions	3,682	1,820
Reductions related to prior year tax positions		(45,305)	(50)
Additions related to current year tax positions	56,383	70,444	139,473
Balance at the end of the year	$ 269,508	$ 209,443	$ 182,484

Income Taxes - Summary of Remai

Income Taxes - Summary of Remaining Balances Recorded in Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Uncertainties [Abstract]
Total unrecognized tax benefits balance	$ 269,508	$ 209,443	$ 182,484	$ 43,061
Amounts netted against related deferred tax assets	(263,696)	(208,307)
Unrecognized tax benefits recorded on consolidated balance sheets	$ 5,812	$ 1,136

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Commitments [Line Items]
Amended revolving credit agreement, leverage ratio above which security will be requited	2.50%
Amended revolving credit agreement, outstanding amount above which security will be requited	$ 500,000,000
Amended revolving credit agreement, percentage of borrowed amount to borrowing capacity above which security will be requited	50.00%
Expiration year of operating lease, earliest	2,017
Expiration year of operating lease, last	2,028
Operating leases, rent expense, net of sublease income	$ 155,700,000	$ 119,800,000	$ 73,900,000
Non-cancelable commitments	$ 138,400,000
Minimum
Other Commitments [Line Items]
Commitments due period	1 year
Maximum
Other Commitments [Line Items]
Commitments due period	3 years
Revolving Credit Facility
Other Commitments [Line Items]
Unsecured revolving credit facility	$ 1,000,000,000
Line of credit facility, expiration date	Oct. 22, 2018
Line of credit facility, interest rate description	Loans under the credit facility bear interest, at the Company’s option, at (i) a base rate based on the highest of the prime rate, the federal funds rate plus 0.50% and an adjusted LIBOR rate for a one-month interest period plus 1.00%, in each case plus a margin ranging from 0.00% to 0.75% or (ii) an adjusted LIBOR rate plus a margin ranging from 1.00% to 1.75%.
Line of credit facility amount	$ 0
Revolving Credit Facility | Base Rate | Minimum
Other Commitments [Line Items]
Line of credit facility, interest rate	0.00%
Revolving Credit Facility | Base Rate | Maximum
Other Commitments [Line Items]
Line of credit facility, interest rate	0.75%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum
Other Commitments [Line Items]
Line of credit facility, interest rate	1.00%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum
Other Commitments [Line Items]
Line of credit facility, interest rate	1.75%
Revolving Credit Facility | Federal Funds Rate Plus 0.50%
Other Commitments [Line Items]
Line of credit facility, interest rate	0.50%
Revolving Credit Facility | Libor Rate One Month Interest Period Plus 1.00%
Other Commitments [Line Items]
Line of credit facility, interest rate	1.00%

Commitments and Contingencies80

Commitments and Contingencies - Minimum Commitments and Sublease Income Under Non-Cancelable Capital and Operating Lease Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Operating Leases Future Minimum Payments Due [Abstract]
2,017	$ 156,757
2,018	148,157
2,019	116,189
2,020	90,664
2,021	57,937
Thereafter	163,315
Total	733,019
Operating Leases Future Minimum Sublease Income[Abstract]
2,017	(24,101)
2,018	(23,712)
2,019	(16,577)
2,020	(9,038)
2,021	(8,969)
Thereafter	0
Total	(82,397)
Capital Leases Future Minimum Payments Due [Abstract]
2,017	85,886
2,018	45,984
2,019	21,062
2,020	0
2,021	0
Thereafter	0
Total	152,932
Less: Amounts representing interest	5,247
Total capital lease obligation	147,685
Less: Short-term portion	80,848	$ 88,166
Long-term portion	$ 66,837	$ 59,695

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended
	Sep. 30, 2015	Oct. 22, 2015
Square Inc
Related Party Transaction [Line Items]
Agreement consideration amount	$ 0
Jack Dorsey Trust
Related Party Transaction [Line Items]
Number of shares given back and contributed by Chief Executive Officer		6,814,085

Segment Information and Opera82

Segment Information and Operations by Geographic Area - Revenue by Services and Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Revenue	$ 2,529,619	$ 2,218,032	$ 1,403,002
United States
Revenue:
Revenue	1,564,776	1,443,240	945,720
International
Revenue:
Revenue	964,843	774,792	457,282
Advertising Services
Revenue:
Revenue	2,248,052	1,994,036	1,255,688
Data Licensing And Other
Revenue:
Revenue	$ 281,567	$ 223,996	$ 147,314

Segment Information and Opera83

Segment Information and Operations by Geographic Area - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)Country	Dec. 31, 2014USD ($)
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 2,529,619	$ 2,218,032	$ 1,403,002
International
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	964,843	$ 774,792	457,282
Revenue | Japan
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 268,500
Revenue | United Kingdom
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue			$ 140,300
Revenue | International
Revenues From External Customers And Long Lived Assets [Line Items]
Number of individual country that contributed in excess of ten percent to revenue | Country		0
Revenue | Geographic Concentration Risk | Japan
Revenues From External Customers And Long Lived Assets [Line Items]
Concentration risk percentage	11.00%
Revenue | Geographic Concentration Risk | United Kingdom
Revenues From External Customers And Long Lived Assets [Line Items]
Concentration risk percentage			10.00%

Segment Information and Opera84

Segment Information and Operations by Geographic Area - Property and Equipment Net by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property and equipment, net:
Property and equipment, net	$ 783,901	$ 735,299
United States
Property and equipment, net:
Property and equipment, net	728,429	683,176
International
Property and equipment, net:
Property and equipment, net	$ 55,472	$ 52,123

Restructuring Charges - Additio

Restructuring Charges - Additional Information (Details) - USD ($) $ in Thousands	Oct. 25, 2016	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost And Reserve [Line Items]
Percentage on employees reduction plan	9.00%
Restructuring and related activities, lease terms expiration year		2,028
Restructuring expenses			$ 12,900
2016 Lease Plan
Restructuring Cost And Reserve [Line Items]
Restructuring expenses		$ 79,685
2016 Lease Plan | Abandonment Excess Office Space
Restructuring Cost And Reserve [Line Items]
Restructuring and related activities, initiation date		Dec. 17, 2016
Restructuring and related activities, lease terms expiration year		2,028

Restructuring Charges - Summary

Restructuring Charges - Summary of Restructuring Charges and Related Liabilities (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost And Reserve [Line Items]
Charges			$ 12,900
Non-cash and other adjustments		$ 25,934	(3,194)
Accrued restructuring, reflected in accrued and other current liabilities		55,942	$ 396
2016 Employee Termination Plan
Restructuring Cost And Reserve [Line Items]
Charges		21,611
Cash payment		(11,629)
Non-cash and other adjustments		(6,357)
Accrued restructuring		3,625
Accrued restructuring, reflected in accrued and other current liabilities	[1]	3,625
2016 Employee Termination Plan | Cost of Revenue
Restructuring Cost And Reserve [Line Items]
Charges		13
2016 Employee Termination Plan | Research and Development
Restructuring Cost And Reserve [Line Items]
Charges		4,246
2016 Employee Termination Plan | Sales and Marketing
Restructuring Cost And Reserve [Line Items]
Charges		17,310
2016 Employee Termination Plan | General and Administrative
Restructuring Cost And Reserve [Line Items]
Charges		42
2016 Lease Plan
Restructuring Cost And Reserve [Line Items]
Charges		79,685
Cash payment		(3,562)
Non-cash and other adjustments		(19,577)
Accrued restructuring		56,546
Accrued restructuring, reflected in accrued and other current liabilities	[1]	52,317
Accrued restructuring, reflected in other long-term liabilities	[1]	4,229
2016 Lease Plan | Cost of Revenue
Restructuring Cost And Reserve [Line Items]
Charges		49,006
2016 Lease Plan | Research and Development
Restructuring Cost And Reserve [Line Items]
Charges		11,693
2016 Lease Plan | Sales and Marketing
Restructuring Cost And Reserve [Line Items]
Charges		13,072
2016 Lease Plan | General and Administrative
Restructuring Cost And Reserve [Line Items]
Charges		$ 5,914
[1]	As of December 31, 2016, the Company’s restructuring accrual included approximately $56.5 million related to the 2016 Lease Plan. This amount is also included the gross operating lease commitment table under Note 14 – Commitments and Contingencies.

Restructuring Charges - Summa87

Restructuring Charges - Summary of Restructuring Charges and Related Liabilities (Parenthetical) (Details) $ in Thousands	Dec. 31, 2016USD ($)
2016 Lease Plan
Restructuring Cost And Reserve [Line Items]
Accrued restructuring	$ 56,546

Schedule II - Valuation and Q88

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Deferred Tax Assets
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 378,448	$ 351,249	$ 227,878
Charged to Expenses	57,529	27,175	155,111
Charged/Credited to Other Accounts	4,016	24	(31,740)
Balance at End of Year	439,993	378,448	351,249
Allowance for Doubtful Accounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	8,121	5,507	2,020
Additions (Reductions)	3,958	5,765	4,632
Write-off/ Adjustments	(4,863)	(3,151)	(1,145)
Balance at End of Year	$ 7,216	$ 8,121	$ 5,507