Twitter (TWTR) 10-K 29 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 17, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
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		697,726,321
Entity Public Float			$ 21,559,514,818

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 911,471	$ 1,510,724
Short-term investments	2,583,877	2,111,154
Accounts receivable, net of allowance for doubtful accounts of $8,121 and $5,507 as of December 31, 2015 and 2014, respectively	638,694	418,454
Prepaid expenses and other current assets	247,750	215,521
Total current assets	4,381,792	4,255,853
Property and equipment, net	735,299	557,019
Intangible assets	141,015	105,011
Goodwill	1,122,728	622,570
Other assets	61,605	42,629
Total assets	6,442,439	5,583,082
Current liabilities:
Accounts payable	134,081	53,241
Accrued and other current liabilities	283,792	228,233
Capital leases, short-term	88,166	112,320
Total current liabilities	506,039	393,794
Convertible notes	1,455,095	1,376,020
Capital leases, long-term	59,695	118,950
Deferred and other long-term tax liabilities, net	2,978	24,706
Other long-term liabilities	50,585	43,209
Total liabilities	$ 2,074,392	$ 1,956,679
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; 694,132 and 642,385 shares issued and outstanding as of December 31, 2015 and 2014, respectively	$ 3	$ 3
Additional paid-in capital	6,507,087	5,208,870
Accumulated other comprehensive loss	(45,566)	(10,024)
Accumulated deficit	(2,093,477)	(1,572,446)
Total stockholders' equity	4,368,047	3,626,403
Total liabilities and stockholders' equity	$ 6,442,439	$ 5,583,082

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 8,121	$ 5,507
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	694,132,000	642,385,000
Common stock, shares outstanding	694,132,000	642,385,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue	$ 2,218,032	$ 1,403,002	$ 664,890
Costs and expenses
Cost of revenue	729,256	446,309	266,718
Research and development	806,648	691,543	593,992
Sales and marketing	871,491	614,110	316,216
General and administrative	260,673	189,906	123,795
Total costs and expenses	2,668,068	1,941,868	1,300,721
Loss from operations	(450,036)	(538,866)	(635,831)
Interest expense	(98,178)	(35,918)	(7,576)
Other income (expense), net	14,909	(3,567)	(3,739)
Loss before income taxes	(533,305)	(578,351)	(647,146)
Benefit from income taxes	(12,274)	(531)	(1,823)
Net loss	$ (521,031)	$ (577,820)	$ (645,323)
Net loss per share attributable to common stockholders:
Basic	$ (0.79)	$ (0.96)	$ (3.41)
Diluted	$ (0.79)	$ (0.96)	$ (3.41)
Weighted-average shares used to compute net loss per share attributable to common stockholders:
Basic	662,424	604,990	189,510
Diluted	662,424	604,990	189,510

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (521,031)	$ (577,820)	$ (645,323)
Other comprehensive income (loss):
Unrealized loss on investments in available-for-sale securities, net of tax	(3,019)	(877)	(76)
Foreign currency translation adjustment	(32,523)	(8,824)	410
Net change in accumulated other comprehensive loss	(35,542)	(9,701)	334
Comprehensive loss	$ (556,573)	$ (587,521)	$ (644,989)

CONSOLIDATED STATEMENTS OF REDE

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Redeemable Convertible Preferred Stock	Convertible Preferred Stock	Common Stock	Common StockRedeemable Convertible Preferred Stock	Common StockConvertible Preferred Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance, beginning of period at Dec. 31, 2012		$ 37,106	$ 835,430	$ 1			$ 101,787	$ (657)	$ (349,303)
Balance, beginning of period, shares at Dec. 31, 2012		3,569	329,575	125,597
Forfeiture of restricted stock, shares		(45)
Conversion of preferred stock to common stock		$ (37,106)	$ (835,430)			$ 2	872,534
Conversion of preferred stock to common stock, shares		(3,524)	(329,575)		3,524	329,575
Balance, end of period at Dec. 31, 2013	$ 2,950,006			$ 3			3,944,952	(323)	(994,626)
Balance, end of period, shares at Dec. 31, 2013	569,922			569,922
Issuance of stock in connection with acquisitions							335,913
Issuance of stock in connection with acquisitions, shares				17,665
Issuance of restricted stock in connection with acquisitions accounted for stock-based compensation, shares				5,775
Exercise of stock options							8,751
Exercise of stock options, shares				7,408
Issuance of common stock upon initial public offering							2,019,741
Issuance of common stock upon initial public offering, shares				80,500
Other activities, shares				(122)
Shares withheld related to net share settlement of equity awards							(14,637)
Stock-based compensation							596,148
Reclassification of preferred stock liability and preferred stock warrant liability to additional paid-in capital							24,241
Other activities							474
Other comprehensive income (loss)	$ 334							334
Net loss	(645,323)								(645,323)
Conversion of preferred stock to common stock, shares						329,575
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				42,748
Issuance of stock in connection with acquisitions							147,958
Issuance of stock in connection with acquisitions, shares				3,326
Issuance of restricted stock in connection with acquisitions accounted for 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	1,900			1,887
Issuance of common stock upon initial public offering							(240)
Shares withheld related to net share settlement of equity awards, shares				(307)
Other activities, shares				25
Shares withheld related to net share settlement of equity awards							(17,053)
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							1,514
Other comprehensive income (loss)	$ (9,701)							(9,701)
Net loss	(577,820)								(577,820)
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	642,132			694,132
Issuance of common stock in connection with RSU vesting, shares				24,002
Issuance of stock in connection with acquisitions							516,538
Issuance of stock in connection with acquisitions, shares				13,613
Issuance of restricted stock in connection with acquisitions accounted for stock-based compensation, shares				2,533
Exercise of stock options							17,914
Exercise of stock options, shares	10,992			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, shares				(281)
Other activities, shares				(637)
Shares withheld related to net share settlement of equity awards							(11,101)
Stock-based compensation							729,193
Other activities							$ 6,378
Other comprehensive income (loss)	$ (35,542)							$ (35,542)
Net loss	$ (521,031)								$ (521,031)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net loss	$ (521,031)	$ (577,820)	$ (645,323)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	312,823	208,165	110,894
Shared Based Compensation net of restructuring	678,924
Stock-based compensation expense	682,118	631,597	600,367
Amortization of discount on convertible notes	69,185	18,823
Provision for bad debt	5,765	4,632	1,557
Deferred income tax benefit	(28,125)	(9,609)	(8,902)
Other adjustments	1,438	7,983	4,161
Changes in assets and liabilities, net of assets acquired and liabilities assumed from acquisitions:
Accounts receivable	(216,585)	(177,583)	(112,060)
Prepaid expenses and other assets	(50,170)	(165,395)	(12,045)
Accounts payable	76,355	18,059	7,957
Accrued and other liabilities	54,487	122,944	54,792
Net cash provided by operating activities	383,066	81,796	1,398
Cash flows from investing activities
Purchases of property and equipment	(347,280)	(201,630)	(75,744)
Purchases of marketable securities	(3,683,488)	(2,937,033)	(1,573,489)
Proceeds from maturities of marketable securities	2,821,745	2,029,518	355,270
Proceeds from sales of marketable securities	383,413	188,092	42,816
Changes in restricted cash	(3,549)	(11,042)	(10,847)
Business combinations, net of cash acquired	(51,644)	(163,477)	(8,072)
Other investing activities	(21,618)	(1,700)	(36,000)
Net cash used in investing activities	(902,421)	(1,097,272)	(1,306,066)
Cash flows from financing activities
Net proceeds from issuance of common stock upon initial public offering			2,018,579
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	(11,101)	(17,053)	(14,637)
Repayments of capital lease obligations	(117,535)	(103,135)	(70,445)
Proceeds from exercise of stock options	17,361	28,658	8,679
Proceeds from issuances of common stock under employee stock purchase plan	39,295	42,402
Other financing activities	8,982	(1,443)
Net cash provided by (used in) financing activities	(62,998)	1,691,722	1,942,176
Net increase (decrease) in cash and cash equivalents	(582,353)	676,246	637,508
Foreign exchange effect on cash and cash equivalents	(16,900)	(6,532)	174
Cash and cash equivalents at beginning of period	1,510,724	841,010	203,328
Cash and cash equivalents at end of period	911,471	1,510,724	841,010
Supplemental cash flow data
Interest paid in cash	15,985	10,000	6,850
Taxes paid in cash	8,229	14,895	2,391
Supplemental disclosures of non-cash investing and financing activities
Conversion of preferred stock to common stock			872,536
Common stock issued in connection with acquisitions	516,538	147,958	331,766
Equipment purchases under capital leases	31,215	140,685	155,722
Changes in accrued equipment purchases	$ 3,902	$ 6,562	(1,602)
Unpaid deferred offering costs			$ 1,162

The Company

The Company	12 Months Ended
	Dec. 31, 2015
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, developers and platform and data partners.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
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, 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 with the resulting expense recognized over the respective period during which the award recipient is required to provide service. Pre-2013 RSUs, as defined and further described in Note 12— Common Stock and Stockholders’ Equity Post-2013 RSUs, as defined and further described in Note 12— Common Stock and Stockholders’ Equity 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. The Company estimates the forfeiture rate based on historical forfeitures of stock-based awards and adjusts 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 in accordance with Accounting Standards Codification (“ASC”) Topic 805 Business Combinations Costs to exit or restructure certain activities of an acquired company or the Company’s internal operations are accounted for as one-time termination and exit costs and are accounted for separately from the business combination. Restructuring and other acquisition-related costs are expensed as incurred. 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 enters into server and networking equipment lease arrangements with original lease terms ranging from three to four years. The classification of each lease arrangement is determined in accordance with the criteria outlined in ASC Topic 840 Leases 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, 2015 and 2014, the Company has recorded restricted cash balances of $3.0 million and $2.6 million, respectively, within prepaid expenses and other current assets and $31.1 million and $28.3 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 related to certain operating lease arrangements. 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 $9.1 million, $1.9 million, and $0.7 million during the years ended December 31, 2015, 2014 and 2013, 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, 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, 2015 and 2014, 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, 2015, 2014 and 2013. The Company’s note hedge transactions, entered into in connection with the Notes, and its derivative financial instruments expose the Company to credit risk to the extent that its counterparties may be unable to meet the terms of the transactions. The Company mitigates this risk by limiting its counterparties to major financial institutions. 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 fixture 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 year ended December 31, 2015, the Company capitalized $5.0 million of interest expense. Capitalized interest was not material in 2014. No interest was capitalized in 2013. 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 2015 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, which range from one 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. See Note 6— Goodwill and Intangible Assets Fair Value Measurements The Financial Accounting Standards Board (the “FASB”)’s authoritative guidance on fair value measurements establishes a framework for measuring fair value and requires disclosure about the fair value measurements of assets and liabilities. This guidance requires the Company to classify and disclose 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. The guidance defines fair value 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 guidance describes three levels of inputs that may be used to measure fair value: 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, 2015, 2014 and 2013, the Company capitalized costs totaling approximately $92.8 million, $79.5 million and $35.6 million, respectively. Capitalized internal use software development costs are included in property and equipment, net. Included in the capitalized amounts above are $50.3 million, $40.8 million and $13.6 million of stock-based compensation expense in the years ended December 31, 2015, 2014 and 2013, 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, 2015, 2014 and 2013, the amortization of capitalized costs included in cost of revenue totaled approximately $37.8 million, $15.2 million and $6.7 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. 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 $119.7 million, $46.6 million and $3.1 million for the years ended December 31, 2015, 2014 and 2013 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 adjustment. Recent Accounting Pronouncements 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. In July 2015, the FASB decided to delay the effective date of the guidance by one year and permit early adoption for annual and interim periods beginning after December 15, 2016. As a result of the revision, 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. The Company has not yet selected a transition method and is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In June 2014, the 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015 and can be applied either prospectively or retrospectively to all awards outstanding as of the beginning of the earliest annual period presented as an adjustment to opening retained earnings. Early adoption is permitted. Adoption of this new accounting standard update is expected to have 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 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted, but the guidance must be applied as of the beginning of the fiscal year containing the adoption date. Adoption of this new accounting standard update is not expected to have a material 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. Adoption of this new accounting standard update is not expected to have a material 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. Adoption of this new accounting standard update is not expected to have a material impact on the Company’s financial statements. In November 2015, the FASB issued a new accounting standard update on simplifying the presentation of deferred income taxes. The new guidance requires that the deferred tax liabilities and assets be classified as noncurrent in the balance sheet. 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 early adopted this guidance prospectively for the year ended December 31, 2015. The adoption of this guidance resulted in a reclassification of the net current deferred tax assets to noncurrent deferred tax assets on the Company’s consolidated balance sheet at December 31, 2015. No prior periods were retroactively adjusted.

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-term Investments	12 Months Ended
	Dec. 31, 2015
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, 2015 2014 Cash and cash equivalents: Cash $ 300,363 $ 147,848 Money market funds 141,700 882,443 U.S. government and agency securities including treasury bills — 271,418 Corporate notes, certificates of deposit and commercial paper 469,408 209,015 Total cash and cash equivalents $ 911,471 $ 1,510,724 Short-term investments: U.S. government and agency securities including treasury bills $ 1,156,418 $ 1,009,541 Corporate notes, certificates of deposit and commercial paper 1,427,459 1,101,613 Total short-term investments $ 2,583,877 $ 2,111,154 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, 2015 and 2014 (in thousands): 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 December 31, 2014 Gross Gross Gross Aggregated Amortized Unrealized Unrealized Estimated Costs Gains Losses Fair Value U.S. government and agency securities including treasury bills $ 1,009,827 $ 8 $ (294 ) $ 1,009,541 Corporate notes, certificates of deposit and commercial paper 1,102,275 4 (666 ) 1,101,613 Total available-for-sale securities classified as short-term investments $ 2,112,102 $ 12 $ (960 ) $ 2,111,154 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, 2015 were as follows (in thousands): December 31, 2015 Aggregated Estimated Fair Value Due within one year $ 1,912,531 Due after one year through two years 671,346 Total $ 2,583,877 There were no securities in a continuous loss position for 12 months or longer as of December 31, 2015 and 2014. 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 up to (or beyond) the initial cost of investment for these securities.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 based on the three-tier fair value hierarchy (in thousands): 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 forward contracts — 6,804 — 6,804 Total $ 171,653 $ 3,030,136 $ — $ 3,201,789 Liabilities Other current liabilities: Foreign currency forward contracts — 3,005 — 3,005 Total $ — $ 3,005 $ — $ 3,005 December 31, 2014 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 882,443 $ — $ — $ 882,443 Treasury bills 73,525 — — 73,525 U.S. government securities — 157,895 — 157,895 Agency securities — 39,998 — 39,998 Corporate notes — 13,684 — 13,684 Commercial paper — 185,321 — 185,321 Certificates of deposit — 10,010 — 10,010 Short-term investments: Treasury bills 167,575 — — 167,575 U.S. government securities — 746,128 — 746,128 Agency securities — 95,838 — 95,838 Corporate notes — 551,604 — 551,604 Commercial paper — 300,589 — 300,589 Certificates of deposit — 249,420 — 249,420 Total $ 1,123,543 $ 2,350,487 $ — $ 3,474,030 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, 2015 was approximately $797.4 million and $797.9 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 December 31, 2015. 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 forward contracts outstanding was equivalent to $425.2 million at December 31, 2015. There were no outstanding foreign currency forward contracts as of December 31, 2014. The fair values of outstanding derivative instruments for the periods presented on a gross basis are as follows (in thousands): December 31, Balance Sheet Location 2015 Assets Foreign currency forward contracts not designated as hedging instruments Other current assets $ 6,804 Liabilities Foreign currency forward contracts not designated as hedging instruments Other current liabilities 3,005 Total $ 3,799 The Company recognized $0.4 million gains on the foreign currency contracts in the year ended December 31, 2015. 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, 2015
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, 2015 2014 Property and equipment, net Equipment $ 720,421 $ 584,561 Furniture and leasehold improvements 297,274 131,851 Capitalized software 211,241 82,052 Construction in progress 85,073 89,806 Total 1,314,009 888,270 Less: Accumulated depreciation and amortization (578,710 ) (331,251 ) Property and equipment, net $ 735,299 $ 557,019 The gross carrying amount of property and equipment includes $370.3 million and $411.3 million of server and networking equipment acquired under capital leases as of December 31, 2015 and 2014, respectively. The accumulated depreciation of the equipment under capital leases totaled $226.9 million and $182.4 million as of December 31, 2015 and 2014, respectively. Depreciation expense totaled $257.2 million, $171.6 million and $94.4 million for the years ended December 31, 2015, 2014 and 2013, respectively. Included in these amounts were depreciation expense for server and networking equipment acquired under capital leases in the amount of $118.7 million, $108.7 million and $70.4 million for the years ended December 31, 2015, 2014 and 2013, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2015
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, 2013 $ 363,477 Gnip acquisition 104,747 Other acquisitions 155,054 Foreign currency translation adjustment (708 ) 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 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, 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 December 31, 2014: Patents and developed technologies $ 105,052 $ (23,165 ) $ 81,887 Publisher and advertiser relationships 32,000 (9,831 ) 22,169 Assembled workforce 1,960 (1,457 ) 503 Other intangible assets 1,100 (648 ) 452 Total $ 140,112 $ (35,101 ) $ 105,011 Patents and developed technologies are amortized over a period ranging from one to eleven years from the respective purchase dates. Publisher and advertiser relationships are amortized over a period ranging from two to six 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, 2015 and 2014 was $54.7 million and $36.6 million, respectively. During the year ended December 31, 2015, $19.0 million in gross carrying value and accumulated amortization related to fully amortized intangible assets was eliminated. Estimated future amortization expense as of December 31, 2015 is as follows (in thousands): Years ending December 31, 2016 $ 44,009 2017 29,283 2018 22,730 2019 15,136 2020 12,640 Thereafter 17,217 Total $ 141,015

Other Balance Sheet Components

Other Balance Sheet Components	12 Months Ended
	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Other Balance Sheet Components	Note 7. Other Balance Sheet Components Prepaid expenses and other current assets The following table presents the detail of prepaid and other current assets for the periods presented (in thousands): December 31, December 31, 2015 2014 Deferred income tax assets, net $ — $ 25,882 Prepaid and other 247,750 189,639 Total $ 247,750 $ 215,521 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, 2015 2014 Accrued compensation $ 90,906 $ 68,000 Accrued sales and marketing expenses 27,948 25,264 Accrued tax liabilities 25,880 18,380 Deferred revenue 23,674 18,679 Accrued publisher and ad network costs 23,486 27,996 Accrued other 91,898 69,914 Total $ 283,792 $ 228,233

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Acquisitions	Note 8. Acquisitions 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 is 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 acquisition of TellApart has been accounted for as a business combination. The fair value of assets acquired and liabilities assumed at the acquisition date was based on a preliminary valuation and estimates and assumptions that are subject to change within the measurement period. 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, which are expected to be substantially collected, $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 will be amortized on a straight-line basis over their estimated useful life 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 four 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 eight 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. 2013 Acquisitions In January 2013, the Company acquired Crashlytics, Inc. (“Crashlytics”), a privately-held company based in Cambridge, Massachusetts, which developed mobile application crash reporting and analysis solutions for mobile application developers. The acquisition of Crashlytics has been accounted for as a business combination. The purchase price of $38.2 million paid in the Company’s common stock was allocated as follows: $5.0 million to developed technology, $0.3 million to assets acquired, $0.3 million to deferred tax liability recorded and $0.1 million to liabilities assumed, and the excess $33.3 million of the purchase price over the fair value of net assets acquired was recorded as goodwill. Goodwill is primarily attributable to the Company’s ability to further improve the efficiency and the overall performance of its mobile platform and the value of acquired talent. This goodwill is not deductible for U.S. income tax purposes. Developed technology will be amortized on a straight-line basis over its estimated useful life of 12 months. Under the terms of the acquisition, the Company has the right to the return of shares issued to non-employee investors if specified performance conditions tied to certain key employees’ continued employment at the Company for one year after the acquisition are not met. The fair value of these contingently returnable shares of $6.7 million is included in the purchase price and is classified as part of stockholders’ equity on the consolidated balance sheets. The performance condition was fully satisfied for these shares. In February 2013, the Company acquired Bluefin Labs, Inc. (“Bluefin”), a privately-held company based in Cambridge, Massachusetts, which provided social television analytics services to brand advertisers, agencies and TV networks. The acquisition of Bluefin has been accounted for as a business combination. The purchase price of $67.3 million paid in the Company’s common stock was allocated as follows: $7.4 million to developed technology, $1.8 million to assets acquired and $1.9 million to liabilities assumed based on their estimated fair value on the acquisition date, and the excess $60.0 million of the purchase price over the fair value of net assets acquired was recorded as goodwill. This goodwill is primarily attributable to the potential for future product offering, ability to further enhance the advertiser experience in using the Company’s services and the value of acquired talent. Goodwill is not deductible for U.S. income tax purposes. Developed technology will be amortized on a straight-line basis over its estimated useful life of 18 months. Under the terms of the acquisition, the Company has the right to the return of shares issued to non-employee investors if specified performance conditions tied to certain key employees’ continued employment at the Company for one year after the acquisition are not met. The fair value of these contingently returnable shares of $7.9 million is included in the purchase price and is classified as part of stockholders’ equity on the consolidated balance sheets. The performance condition was fully satisfied for these shares. In October 2013, the Company acquired 100% of the ownership interest in privately held MoPub, Inc. (“MoPub”), a mobile-focused advertising exchange headquartered in San Francisco, California. Under the terms of the acquisition, all of the issued and outstanding shares of capital stock of MoPub, including shares of restricted stock subject to continued employment, were converted into 11.2 million shares of the Company’s common stock and 2.0 million shares of unvested restricted stock, and all equity awards to purchase shares of MoPub common stock held by individuals, who will continue to provide services to the Company, were converted into the right to receive an aggregate of 1.2 million shares of the Company’s stock options. Of the aggregate acquisition consideration, approximately $218.8 million associated with the common stock issued and the fair value attributable to the portion of restricted stock and assumed stock options for which services had been rendered as of the closing of the acquisition was determined to be the accounting purchase price. The purchase price was allocated to the acquired tangible and intangible assets and assumed liabilities based on their estimated fair values at closing as follows: $21.1 million to publisher and advertiser relationships, $12.9 million to developed technology, $1.1 million to trade name, $22.1 million to account receivables acquired, $1.2 million to other tangible assets acquired, $22.1 million to publisher payments liabilities assumed, $4.4 million to other liabilities assumed, $5.5 million to deferred tax liability recorded, and the excess $192.4 million of the purchase price over the fair value of net assets acquired was recorded as goodwill. This goodwill is primarily attributable to the potential expansion of the advertising business across the mobile ecosystem through continued investment in the MoPub exchange and expected synergies arising from the acquisition, the ability to further enhance the advertiser experience by building real-time bidding into the Twitter ads platform and the value of acquired talent. Goodwill is not deductible for U.S. income tax purposes. Publisher and advertiser relationships and developed technology will be amortized on a straight-line basis over their estimated useful life of 36 months, and trade name was amortized on a straight-line basis over its estimated useful life of 24 months. During the year ended December 31, 2013, the Company completed acquisitions of certain intangible assets for the total purchase price of $38.5 million. These transactions were accounted for as a purchase of assets and, accordingly, the total purchase price was allocated to the identifiable intangible assets acquired based on their respective fair values on the acquisition date. As a result of these transactions, the Company recorded intangible assets of $38.5 million, which was comprised of $36.0 million of patents, $2.0 million of assembled workforce and $0.5 million of developed technology. The patents, developed technology and assembled workforce will be amortized on a straight-line basis over their estimated useful lives of 1 to 11 years. During the year ended December 31, 2013, the Company completed acquisitions of five additional companies, which were not individually significant and accounted for as business combinations. The total purchase price for these acquisitions of $13.2 million (paid in shares of the Company’s common stock valued at approximately $7.4 million and cash consideration of $5.8 million) was primarily allocated to $4.5 million of developed technology and $0.2 million of assumed liabilities based on their estimated fair value on the acquisition date, and the excess $8.9 million of the purchase price over the fair value of net assets acquired was recorded as goodwill. Goodwill recorded in relation to these acquisitions is primarily attributable to expected synergies and the value of acquired assembled workforce. Two of the acquisitions resulted in tax-deductible goodwill of $7.3 million for U.S. income tax purposes. Developed technology will be amortized on a straight-line basis over their estimated useful lives of 24 to 36 months. In relation to the 2013 acquisitions, the Company also agreed to pay up to $83.1 million of equity consideration which was to be paid to certain employees of the acquired entities contingent upon their continued employment with the Company. The Company recognizes compensation expense related to the equity consideration over the requisite services periods of up to 48 months from the respective acquisition dates on a straight-line basis. The Company also granted to continuing employees options to purchase a total of 2.0 million shares of common stock in exchange for their outstanding options to purchase the shares of the acquired entities including 1.2 million shares granted in connection with the acquisition of MoPub disclosed above. Excluding the fair value of the stock options that was allocated and recorded as part of the purchase price for the portion of the service period completed pre-acquisition, the Company will recognize approximately $24.5 million of stock-based compensation expense in relation to these stock options over the remaining requisite service periods of up to 48 months from the respective acquisition dates on a straight-line basis. For business combinations closed in 2013 except for the acquisition of MoPub, the Company has considered all potential identifiable intangible assets and determined that it was not appropriate to allocate material amounts to identifiable intangible assets other than acquired developed technologies. In valuing these acquired developed technologies, the Company determined that neither the income approach nor the market approach was relevant, and, consistent with a market participant approach that would weigh a “make” versus “buy” decision when considering the acquisition of a particular incremental technology, applied the cost approach in determining the amount of purchase price allocated to acquired developed technology. The cost approach uses the concept of reproduction cost as an indicator of fair value. The premise of the cost approach is that a prudent investor would pay no more for an asset than the amount for which the asset could be replaced with a new one. Reproduction cost refers to the cost incurred to reproduce the asset using the exact same specifications. In order to apply the cost method to determine the fair value of each acquired developed technology, the Company considered the following: (i) the estimated development hours or equivalent of person months required to reproduce the technology, (ii) the related labor cost and (iii) an expected market participant profit margin. The Company utilized various forms of the income approach to measure the fair value of the publisher relationships, advertiser relationships, developed technology, and trade name acquired in the acquisition of MoPub. For the publisher relationships, fair value was determined based on the multi-period excess earnings approach which calculates the present value of the after-tax cash flows attributable to the intangible asset only. For the advertiser relationships, fair value was determined based on the distributor method which relies upon market-based distributor data to reasonably isolate the revenue, earnings, and cash flow attributable to sales efforts. For the developed technology and trade names acquired, fair value was determined based on the relief from royalty method, which calculates the present value of the after-tax royalty savings attributable to owning the intangible assets. For certain transactions that were considered asset acquisitions, the Company identified assembled workforce as an intangible asset. The Company used the cost approach to value the assembled workforce. The cost approach takes into consideration the relevant costs to replace the workforce, which include recruiting and training costs required until the employees become fully integrated. 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. Revenue and loss from operations arising from the acquisitions completed in 2013 that are included in the Company’s consolidated statements of operations for 2013 were $9.6 million and $42.3 million, respectively.

Convertible Notes

Convertible Notes	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014, the Company recognized $74.2 million and $18.8 million, respectively, of interest expense related to the amortization of the debt discount. As of December 31, 2015, the net carrying value, net of the initial purchasers’ discount and debt discount, of 2019 Notes and 2021 Notes was $753.0 million and $702.1 million, respectively. The Notes consisted of the following (in thousands): December 31, 2015 December 31, 2014 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) (181,994 ) (251,911 ) (225,104 ) (287,876 ) Net carrying amount $ 753,006 $ 702,089 $ 709,896 $ 666,124 Carrying amount of the equity component (2) $ 222,826 $ 283,283 $ 222,826 $ 283,283 (1) (2) As of December 31, 2015, the remaining life of the 2019 Notes and 2021 Notes is approximately 44 months and 68 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 the consolidated balance sheet as of December 31, 2014.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2015
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. Prior to their conversion to common stock, the Company also considered all series of the Company’s redeemable convertible preferred stock and convertible preferred stock to be participating securities as the holders of the preferred stock were entitled to receive a noncumulative dividend on a pari passu basis in the event that a dividend was 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, 2015, 2014 and 2013, 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, 2015 2014 2013 Net loss $ (521,031 ) $ (577,820 ) $ (645,323 ) Basic shares: Weighted-average common shares outstanding 670,132 613,944 196,675 Weighted-average restricted stock subject to repurchase (7,708 ) (8,954 ) (7,165 ) Weighted-average shares used to compute basic net loss per share 662,424 604,990 189,510 Diluted shares: Weighted-average shares used to compute diluted net loss per share 662,424 604,990 189,510 Net loss per share attributable to common stockholders: Basic $ (0.79 ) $ (0.96 ) $ (3.41 ) Diluted $ (0.79 ) $ (0.96 ) $ (3.41 ) 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, 2015 2014 2013 RSUs 43,170 64,135 95,723 Warrants 24,329 24,329 117 Stock options 11,177 20,420 42,246 Shares subject to repurchase and others 9,146 9,335 12,882 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, 2015
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, 2015 and 2014, there was no preferred stock outstanding.

Common Stock and Stockholders'

Common Stock and Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Stockholders Equity Note [Abstract]
Common Stock and Stockholders' Equity	Note 12. Common Stock and Stockholders’ Equity Common Stock As of December 31, 2015, 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, 2015, 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, 2015 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, 2014 4,955 $ 25.62 Granted 2,467 $ 40.00 Vested (2,534 ) $ 24.31 Canceled (348 ) $ 29.34 Unvested restricted common stock at December 31, 2015 4,540 $ 33.88 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, 2015, the total number of options and RSUs outstanding under the 2013 Equity Incentive Plan was 28.9 million shares, and 113.1 million shares were available for future issuance. There were 23.3 million shares of options and RSUs outstanding under the 2007 Equity Incentive Plan as of December 31, 2015. No additional shares will be issued under the 2007 Equity Incentive Plan. Options granted under the Company’s Equity Incentive Plans generally expire 10 years after the grant date. The Company issues new shares to satisfy stock option exercises. Under the 2007 Equity Incentive Plan, RSUs granted to domestic and international employees prior to February 2013 (“Pre-2013 RSUs”) vest upon the satisfaction of both a service condition and a performance condition. The service condition for these awards is generally satisfied over four years. RSUs granted to domestic employees starting in February 2013 (“Post-2013 RSUs”) are not subject to a performance condition in order to vest. The majority of Post-2013 RSUs vest over a service period of four years. Pursuant to the terms of the 2007 Equity Incentive Plan and the 2013 Equity Incentive Plan, the shares underlying Post-2013 RSUs that satisfy the service condition are to be delivered to holders no later than the fifteenth day of the third month following the end of the calendar year the service condition is satisfied, or if later, the end of the Company’s tax year. The Company undertook a net settlement of vested RSUs held by the executive officers upon settlement of their Pre-2013 RSUs in 2014, withheld shares and remitted income tax on behalf of the applicable executive officers of $17.1 million in cash at the applicable minimum statutory rates in the year ended December 31, 2014. The shares that were withheld by the Company as a result of the net settlement of RSUs are no longer considered issued and outstanding. 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, 2015 and 2014, employees purchased an aggregate of 1.5 million and 1.9 million shares, respectively, under this plan at a weighted average price of $25.78 and $22.47 per share, respectively. Stock Option Activity A summary of stock option activity for the year ended December 31, 2015 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, 2014 20,420 $ 3.33 5.78 $ 667,538 Options granted and assumed in connection with acquisitions 2,212 $ 12.34 Options exercised (10,992 ) $ 1.58 Options canceled (463 ) $ 10.05 Outstanding at December 31, 2015 11,177 $ 6.55 5.86 $ 199,576 Vested and expected to vest at December 31, 2015 (1) 10,383 $ 5.56 5.65 $ 192,696 Exercisable at December 31, 2015 8,526 $ 3.49 5.13 $ 170,483 (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, 2015, 2014 and 2013 were $337.2 million, $872.8 million and $123.7 million, respectively. RSU Activity The following table summarizes the activity related to the Company’s RSUs for the year ended December 31, 2015. 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, 2014 64,135 $ 29.08 Granted 18,493 $ 35.45 Vested (24,002 ) $ 27.58 Canceled (15,456 ) $ 29.60 Unvested and outstanding at December 31, 2015 43,170 $ 32.46 The total fair value of RSUs vested during the years ended December 31, 2015 and December 31, 2014 was approximately $849.8 million and $2.02 billion, 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, 2015, 2014 and 2013 is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Cost of revenue $ 40,705 $ 50,536 $ 50,942 Research and development 401,537 360,726 379,913 Sales and marketing 156,904 157,263 114,440 General and administrative 82,972 63,072 55,072 Total $ 682,118 $ 631,597 $ 600,367 Upon completion of the Company’s initial public offering in November 2013, the Company began recording stock-based compensation expense related to Pre-2013 RSUs because the satisfaction of the performance condition for vesting became probable. During the year ended December 31, 2013, the amount of stock-based compensation expense recorded in relation to Pre-2013 RSUs totaled approximately $433.5 million and was comprised of $405.9 million of expense accumulated until the effective date of the initial public offering for awards vested and $27.6 million of subsequent recognition of expense during the year as additional Pre-2013 RSUs continued to vest. During the year ended December 31, 2014, the Company recorded $84.4 million of expense in relation to Pre-2013 RSUs as the stock-based compensation continued to be amortized for outstanding Pre-2013 RSUs on an accelerated basis. 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, 2015 and 2013, respectively. Income tax benefits recognized for stock-based compensation arrangements during the years ended December 31, 2015, 2014 and 2013 were not material. The Company capitalized $50.3 million, $40.8 million and $13.6 million of stock-based compensation expense associated with the cost for developing software for internal use in the years ended December 31, 2015, 2014 and 2013, respectively. As of December 31, 2015, there was $1.25 billion of unamortized stock-based compensation expense related to unvested awards which is expected to be recognized over a weighted-average period of 2.51 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
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, 2015, 2014 and 2013 are as follows (in thousands): Year Ended December 31, 2015 2014 2013 Domestic $ (201,628 ) $ (164,854 ) $ (549,397 ) Foreign (331,677 ) (413,497 ) (97,749 ) Loss before income taxes $ (533,305 ) $ (578,351 ) $ (647,146 ) The components of the benefit from income taxes for the years ended December 31, 2015, 2014 and 2013 are as follows (in thousands): Year Ended December 31, 2015 2014 2013 Current: Federal $ — $ — $ — State 1,226 720 857 Foreign 14,625 8,358 6,222 Total current provision for income taxes 15,851 9,078 7,079 Deferred: Federal (23,208 ) (8,972 ) (5,412 ) State (852 ) (128 ) (453 ) Foreign (4,065 ) (509 ) (3,037 ) Total deferred benefit for income taxes (28,125 ) (9,609 ) (8,902 ) Benefit from income taxes $ (12,274 ) $ (531 ) $ (1,823 ) 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, 2015, 2014 and 2013: Year Ended December 31, 2015 2014 2013 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit (0.1 ) (0.1 ) (0.1 ) Stock-based compensation (2.9 ) (4.2 ) (2.9 ) Research and development credits 7.2 25.2 3.6 Valuation Allowance 3.1 (9.4 ) (25.0 ) Nondeductible expenses (5.6 ) (4.5 ) (3.0 ) Foreign rate differential (23.7 ) (26.4 ) (5.8 ) Change in tax positions (10.7 ) (15.9 ) (2.0 ) Other 0.0 0.4 0.5 Effective tax rate 2.3 % 0.1 % 0.3 % The tax effects of temporary differences and related deferred tax assets and liabilities as of December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 242,987 $ 230,417 Accruals and reserves 36,133 20,496 Stock-based compensation expense 80,106 89,159 Research and development credits 209,425 168,934 California Enterprise Zone Credit 11,710 10,355 Fixed assets and intangible assets 1,457 — Other 7,059 3,145 Total deferred tax assets 588,877 522,506 Valuation allowance (378,448 ) (351,249 ) Total deferred tax assets, net of valuation allowance 210,429 171,257 Deferred tax liabilities: Fixed assets and intangible assets (174,007 ) (132,671 ) Convertible notes (30,002 ) (35,133 ) Other (1,577 ) (420 ) Total deferred tax liabilities (205,586 ) (168,224 ) Net deferred tax assets $ 4,843 $ 3,033 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, 2015. Accordingly, the Company has established a full valuation allowance against its U.S. and Brazil deferred tax assets. As of December 31, 2015, the Company has net $5.2 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, 2015, the Company has not provided for income taxes on $82.4 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, 2015, the Company had $3.37 billion of federal and $1.34 billion of state net operating loss carryforwards available to reduce future taxable income, which will begin to expire in 2027 for federal and 2016 for state tax purposes. Pursuant to authoritative guidance, the excess tax benefit from stock-based compensation will only be recorded to stockholders’ equity when cash taxes payable are reduced. As of December 31, 2015, the portion of net operating loss carryforwards related to the excess tax benefit from stock-based compensation was approximately $3.35 billion, the benefit of which will be credited to additional paid-in capital when realized The Company also has research credit carryforwards of $188.2 million and $150.6 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 $18.0 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, 2015, the unrecognized tax benefit was $209.4 million, materially all of which would result in corresponding adjustments to valuation allowance. A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance at the beginning of the year $ 182,484 $ 43,061 $ 23,352 Additions related to prior year tax positions 1,820 — 7,880 Reductions related to prior year tax positions (45,305 ) (50 ) — Additions related to current year tax positions 70,444 139,473 11,829 Balance at the end of the year $ 209,443 $ 182,484 $ 43,061 Total unrecognized tax benefits are recorded on the Company’s consolidated balance sheets as follows (in thousands): December 31, 2015 2014 Total unrecognized tax benefits balance $ 209,443 $ 182,484 Amounts netted against related deferred tax assets (208,307 ) (181,786 ) Unrecognized tax benefits recorded on consolidated balance sheets $ 1,136 $ 698 The net unrecognized tax benefit of $1.1 million and $0.7 million as of December 31, 2015 and 2014, respectively, was included in the deferred and other long-term tax liabilities, net on the Company’s consolidated balance sheets. The Company adopted new guidance on the financial statement presentation of unrecognized tax benefits prospectively as of January 1, 2014. The application of this guidance resulted in a $15.8 million decrease in net deferred tax assets and the related liability for unrecognized tax benefits upon adoption. 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, 2015 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 federal tax return based upon the opinion rendered in this case, which resulted in an increase in the 2014 net operating loss 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. In the third quarter of 2015, the Company concluded its California income tax examination for tax years 2010 and 2011 with adjustments that immaterially impacted the deferred tax balances with an offset to the valuation allowance, resulting in no additional net tax expense or benefit. However, the Company’s California R&D tax credit carryforward attributes remain open and subject to examination in future years until used. The Company believes that adequate amounts have been reserved in these jurisdictions. The Company’s 2007 to 2015 tax years remain subject to examination by the United States and California, and its 2011 to 2015 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, 2015
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, 2015, 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 2016 and 2026. The Company also has lease arrangements for certain server and networking equipment. . A summary of gross and net lease commitments as of December 31, 2015 is as follows (in thousands): Operating Capital Leases Leases Years ending December 31, 2016 $ 148,001 $ 93,001 2017 155,213 49,454 2018 149,298 10,739 2019 116,764 592 2020 105,086 — Thereafter 243,788 — $ 918,150 153,786 Less: Amounts representing interest 5,925 Total capital lease obligation 147,861 Less: Short-term portion 88,166 Long-term portion $ 59,695 Rent expense under the Company’s operating leases, including co-location arrangements for the Company’s data centers, was $119.8 million, $73.9 million and $35.4 million for the years ended December 31, 2015, 2014 and 2013, respectively. Non-cancelable Obligations The Company also had $166.3 million of non-cancelable contractual commitments as of December 31, 2015, 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. 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, 2015, 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, 2015, 2014 and 2013 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, 2015 and 2014.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
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 at the annual meeting of stockholders to be held in 2016, the same number of shares will be granted over time to employees and other service providers. The contribution will be recorded as a treasury stock transaction in stockholders’ equity when and if approved by the Company’s stockholders.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2015
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, 2015
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, 2015 2014 2013 Revenue by services: Advertising services $ 1,994,036 $ 1,255,688 $ 594,546 Data licensing and other 223,996 147,314 70,344 Total revenue $ 2,218,032 $ 1,403,002 $ 664,890 Year Ended December 31, 2015 2014 2013 Revenue by geographic area: United States $ 1,443,240 $ 945,720 $ 492,320 International 774,792 457,282 172,570 Total revenue $ 2,218,032 $ 1,403,002 $ 664,890 No individual country from the international markets contributed in excess of 10% of the total revenue for the year ended December 31, 2015. The United Kingdom accounted for $140.3 million and $66.5 million or 10% of the total revenue for each of the years ended December 31, 2014 and 2013, respectively. Property and Equipment, net The following table sets forth property and equipment, net by geographic area (in thousands): December 31, December 31, 2015 2014 Property and equipment, net: United States $ 683,176 $ 523,810 International 52,123 33,209 Total property and equipment, net $ 735,299 $ 557,019

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2015
Restructuring And Related Activities [Abstract]
Restructuring Charges	Note 18. Restructuring Charges In October 2015, the Company initiated a restructuring and reduction in force plan to exit approximately 8% of the Company’s global workforce. The Company incurred $16.1 million of cash expenditures, substantially all of which was severance costs. Total restructuring expenses was $12.9 million, which was lower than cash restructuring costs due to a credit related to non-cash stock-based compensation expense reversals for unvested stock awards. The restructuring and reduction in force plan was substantially completed in 2015. The remaining accrued liability for the restructuring plan was not material as of December 31, 2015.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
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, 2015, 2014 AND 2013 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, 2015 $ 351,249 $ 27,175 $ 24 $ 378,448 Year ended December 31, 2014 $ 227,878 $ 155,111 $ (31,740 ) $ 351,249 Year ended December 31, 2013 $ 42,175 $ 180,691 $ 5,012 $ 227,878 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, 2015 $ 5,507 $ 5,765 $ (3,151 ) $ 8,121 Year ended December 31, 2014 $ 2,020 $ 4,632 $ (1,145 ) $ 5,507 Year ended December 31, 2013 $ 1,280 $ 1,557 $ (817 ) $ 2,020 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).

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
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, 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 with the resulting expense recognized over the respective period during which the award recipient is required to provide service. Pre-2013 RSUs, as defined and further described in Note 12— Common Stock and Stockholders’ Equity Post-2013 RSUs, as defined and further described in Note 12— Common Stock and Stockholders’ Equity 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. The Company estimates the forfeiture rate based on historical forfeitures of stock-based awards and adjusts 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 in accordance with Accounting Standards Codification (“ASC”) Topic 805 Business Combinations Costs to exit or restructure certain activities of an acquired company or the Company’s internal operations are accounted for as one-time termination and exit costs and are accounted for separately from the business combination. Restructuring and other acquisition-related costs are expensed as incurred.
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 enters into server and networking equipment lease arrangements with original lease terms ranging from three to four years. The classification of each lease arrangement is determined in accordance with the criteria outlined in ASC Topic 840 Leases
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, 2015 and 2014, the Company has recorded restricted cash balances of $3.0 million and $2.6 million, respectively, within prepaid expenses and other current assets and $31.1 million and $28.3 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 related to certain operating lease arrangements. 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 $9.1 million, $1.9 million, and $0.7 million during the years ended December 31, 2015, 2014 and 2013, 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, 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, 2015 and 2014, 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, 2015, 2014 and 2013. The Company’s note hedge transactions, entered into in connection with the Notes, and its derivative financial instruments expose the Company to credit risk to the extent that its counterparties may be unable to meet the terms of the transactions. The Company mitigates this risk by limiting its counterparties to major financial institutions.
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 fixture 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 year ended December 31, 2015, the Company capitalized $5.0 million of interest expense. Capitalized interest was not material in 2014. No interest was capitalized in 2013.
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 2015 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, which range from one 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. See Note 6— Goodwill and Intangible Assets
Fair Value Measurements	Fair Value Measurements The Financial Accounting Standards Board (the “FASB”)’s authoritative guidance on fair value measurements establishes a framework for measuring fair value and requires disclosure about the fair value measurements of assets and liabilities. This guidance requires the Company to classify and disclose 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. The guidance defines fair value 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 guidance describes three levels of inputs that may be used to measure fair value: 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, 2015, 2014 and 2013, the Company capitalized costs totaling approximately $92.8 million, $79.5 million and $35.6 million, respectively. Capitalized internal use software development costs are included in property and equipment, net. Included in the capitalized amounts above are $50.3 million, $40.8 million and $13.6 million of stock-based compensation expense in the years ended December 31, 2015, 2014 and 2013, 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, 2015, 2014 and 2013, the amortization of capitalized costs included in cost of revenue totaled approximately $37.8 million, $15.2 million and $6.7 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.
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 $119.7 million, $46.6 million and $3.1 million for the years ended December 31, 2015, 2014 and 2013 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 adjustment.
Recent Accounting Pronouncements	Recent Accounting Pronouncements 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. In July 2015, the FASB decided to delay the effective date of the guidance by one year and permit early adoption for annual and interim periods beginning after December 15, 2016. As a result of the revision, 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. The Company has not yet selected a transition method and is evaluating the impact of adopting this new accounting standard update on the financial statements and related disclosures. In June 2014, the 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015 and can be applied either prospectively or retrospectively to all awards outstanding as of the beginning of the earliest annual period presented as an adjustment to opening retained earnings. Early adoption is permitted. Adoption of this new accounting standard update is expected to have 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 will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted, but the guidance must be applied as of the beginning of the fiscal year containing the adoption date. Adoption of this new accounting standard update is not expected to have a material 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. Adoption of this new accounting standard update is not expected to have a material 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. This guidance will be effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. Adoption of this new accounting standard update is not expected to have a material impact on the Company’s financial statements. In November 2015, the FASB issued a new accounting standard update on simplifying the presentation of deferred income taxes. The new guidance requires that the deferred tax liabilities and assets be classified as noncurrent in the balance sheet. 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 early adopted this guidance prospectively for the year ended December 31, 2015. The adoption of this guidance resulted in a reclassification of the net current deferred tax assets to noncurrent deferred tax assets on the Company’s consolidated balance sheet at December 31, 2015. No prior periods were retroactively adjusted.

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
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 fixture 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, 2015
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, 2015 2014 Cash and cash equivalents: Cash $ 300,363 $ 147,848 Money market funds 141,700 882,443 U.S. government and agency securities including treasury bills — 271,418 Corporate notes, certificates of deposit and commercial paper 469,408 209,015 Total cash and cash equivalents $ 911,471 $ 1,510,724 Short-term investments: U.S. government and agency securities including treasury bills $ 1,156,418 $ 1,009,541 Corporate notes, certificates of deposit and commercial paper 1,427,459 1,101,613 Total short-term investments $ 2,583,877 $ 2,111,154
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, 2015 and 2014 (in thousands): 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 December 31, 2014 Gross Gross Gross Aggregated Amortized Unrealized Unrealized Estimated Costs Gains Losses Fair Value U.S. government and agency securities including treasury bills $ 1,009,827 $ 8 $ (294 ) $ 1,009,541 Corporate notes, certificates of deposit and commercial paper 1,102,275 4 (666 ) 1,101,613 Total available-for-sale securities classified as short-term investments $ 2,112,102 $ 12 $ (960 ) $ 2,111,154
Contractual Maturities of Securities Classified as Available-for-Sale	The contractual maturities of securities classified as available-for-sale as of December 31, 2015 were as follows (in thousands): December 31, 2015 Aggregated Estimated Fair Value Due within one year $ 1,912,531 Due after one year through two years 671,346 Total $ 2,583,877

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 based on the three-tier fair value hierarchy (in thousands): 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 forward contracts — 6,804 — 6,804 Total $ 171,653 $ 3,030,136 $ — $ 3,201,789 Liabilities Other current liabilities: Foreign currency forward contracts — 3,005 — 3,005 Total $ — $ 3,005 $ — $ 3,005 December 31, 2014 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 882,443 $ — $ — $ 882,443 Treasury bills 73,525 — — 73,525 U.S. government securities — 157,895 — 157,895 Agency securities — 39,998 — 39,998 Corporate notes — 13,684 — 13,684 Commercial paper — 185,321 — 185,321 Certificates of deposit — 10,010 — 10,010 Short-term investments: Treasury bills 167,575 — — 167,575 U.S. government securities — 746,128 — 746,128 Agency securities — 95,838 — 95,838 Corporate notes — 551,604 — 551,604 Commercial paper — 300,589 — 300,589 Certificates of deposit — 249,420 — 249,420 Total $ 1,123,543 $ 2,350,487 $ — $ 3,474,030
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, Balance Sheet Location 2015 Assets Foreign currency forward contracts not designated as hedging instruments Other current assets $ 6,804 Liabilities Foreign currency forward contracts not designated as hedging instruments Other current liabilities 3,005 Total $ 3,799

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 2014 Property and equipment, net Equipment $ 720,421 $ 584,561 Furniture and leasehold improvements 297,274 131,851 Capitalized software 211,241 82,052 Construction in progress 85,073 89,806 Total 1,314,009 888,270 Less: Accumulated depreciation and amortization (578,710 ) (331,251 ) Property and equipment, net $ 735,299 $ 557,019

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2013 $ 363,477 Gnip acquisition 104,747 Other acquisitions 155,054 Foreign currency translation adjustment (708 ) 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
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, 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 December 31, 2014: Patents and developed technologies $ 105,052 $ (23,165 ) $ 81,887 Publisher and advertiser relationships 32,000 (9,831 ) 22,169 Assembled workforce 1,960 (1,457 ) 503 Other intangible assets 1,100 (648 ) 452 Total $ 140,112 $ (35,101 ) $ 105,011
Schedule of Estimated Future Amortization Expenses	Estimated future amortization expense as of December 31, 2015 is as follows (in thousands): Years ending December 31, 2016 $ 44,009 2017 29,283 2018 22,730 2019 15,136 2020 12,640 Thereafter 17,217 Total $ 141,015

Other Balance Sheet Components

Other Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Prepaid and Other Current Assets	The following table presents the detail of prepaid and other current assets for the periods presented (in thousands): December 31, December 31, 2015 2014 Deferred income tax assets, net $ — $ 25,882 Prepaid and other 247,750 189,639 Total $ 247,750 $ 215,521
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, 2015 2014 Accrued compensation $ 90,906 $ 68,000 Accrued sales and marketing expenses 27,948 25,264 Accrued tax liabilities 25,880 18,380 Deferred revenue 23,674 18,679 Accrued publisher and ad network costs 23,486 27,996 Accrued other 91,898 69,914 Total $ 283,792 $ 228,233

Convertible Notes (Tables)

Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Components of Notes	The Notes consisted of the following (in thousands): December 31, 2015 December 31, 2014 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) (181,994 ) (251,911 ) (225,104 ) (287,876 ) Net carrying amount $ 753,006 $ 702,089 $ 709,896 $ 666,124 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, 2015
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, 2015 2014 2013 Net loss $ (521,031 ) $ (577,820 ) $ (645,323 ) Basic shares: Weighted-average common shares outstanding 670,132 613,944 196,675 Weighted-average restricted stock subject to repurchase (7,708 ) (8,954 ) (7,165 ) Weighted-average shares used to compute basic net loss per share 662,424 604,990 189,510 Diluted shares: Weighted-average shares used to compute diluted net loss per share 662,424 604,990 189,510 Net loss per share attributable to common stockholders: Basic $ (0.79 ) $ (0.96 ) $ (3.41 ) Diluted $ (0.79 ) $ (0.96 ) $ (3.41 )
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, 2015 2014 2013 RSUs 43,170 64,135 95,723 Warrants 24,329 24,329 117 Stock options 11,177 20,420 42,246 Shares subject to repurchase and others 9,146 9,335 12,882

Common Stock and Stockholders36

Common Stock and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 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, 2014 4,955 $ 25.62 Granted 2,467 $ 40.00 Vested (2,534 ) $ 24.31 Canceled (348 ) $ 29.34 Unvested restricted common stock at December 31, 2015 4,540 $ 33.88
Summary of Stock Option Activity	A summary of stock option activity for the year ended December 31, 2015 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, 2014 20,420 $ 3.33 5.78 $ 667,538 Options granted and assumed in connection with acquisitions 2,212 $ 12.34 Options exercised (10,992 ) $ 1.58 Options canceled (463 ) $ 10.05 Outstanding at December 31, 2015 11,177 $ 6.55 5.86 $ 199,576 Vested and expected to vest at December 31, 2015 (1) 10,383 $ 5.56 5.65 $ 192,696 Exercisable at December 31, 2015 8,526 $ 3.49 5.13 $ 170,483 (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, 2015. 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, 2014 64,135 $ 29.08 Granted 18,493 $ 35.45 Vested (24,002 ) $ 27.58 Canceled (15,456 ) $ 29.60 Unvested and outstanding at December 31, 2015 43,170 $ 32.46
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, 2015, 2014 and 2013 is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Cost of revenue $ 40,705 $ 50,536 $ 50,942 Research and development 401,537 360,726 379,913 Sales and marketing 156,904 157,263 114,440 General and administrative 82,972 63,072 55,072 Total $ 682,118 $ 631,597 $ 600,367

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015, 2014 and 2013 are as follows (in thousands): Year Ended December 31, 2015 2014 2013 Domestic $ (201,628 ) $ (164,854 ) $ (549,397 ) Foreign (331,677 ) (413,497 ) (97,749 ) Loss before income taxes $ (533,305 ) $ (578,351 ) $ (647,146 )
Components of Benefit from Income Taxes	The components of the benefit from income taxes for the years ended December 31, 2015, 2014 and 2013 are as follows (in thousands): Year Ended December 31, 2015 2014 2013 Current: Federal $ — $ — $ — State 1,226 720 857 Foreign 14,625 8,358 6,222 Total current provision for income taxes 15,851 9,078 7,079 Deferred: Federal (23,208 ) (8,972 ) (5,412 ) State (852 ) (128 ) (453 ) Foreign (4,065 ) (509 ) (3,037 ) Total deferred benefit for income taxes (28,125 ) (9,609 ) (8,902 ) Benefit from income taxes $ (12,274 ) $ (531 ) $ (1,823 )
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, 2015, 2014 and 2013: Year Ended December 31, 2015 2014 2013 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit (0.1 ) (0.1 ) (0.1 ) Stock-based compensation (2.9 ) (4.2 ) (2.9 ) Research and development credits 7.2 25.2 3.6 Valuation Allowance 3.1 (9.4 ) (25.0 ) Nondeductible expenses (5.6 ) (4.5 ) (3.0 ) Foreign rate differential (23.7 ) (26.4 ) (5.8 ) Change in tax positions (10.7 ) (15.9 ) (2.0 ) Other 0.0 0.4 0.5 Effective tax rate 2.3 % 0.1 % 0.3 %
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, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 242,987 $ 230,417 Accruals and reserves 36,133 20,496 Stock-based compensation expense 80,106 89,159 Research and development credits 209,425 168,934 California Enterprise Zone Credit 11,710 10,355 Fixed assets and intangible assets 1,457 — Other 7,059 3,145 Total deferred tax assets 588,877 522,506 Valuation allowance (378,448 ) (351,249 ) Total deferred tax assets, net of valuation allowance 210,429 171,257 Deferred tax liabilities: Fixed assets and intangible assets (174,007 ) (132,671 ) Convertible notes (30,002 ) (35,133 ) Other (1,577 ) (420 ) Total deferred tax liabilities (205,586 ) (168,224 ) Net deferred tax assets $ 4,843 $ 3,033
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, 2015 2014 2013 Balance at the beginning of the year $ 182,484 $ 43,061 $ 23,352 Additions related to prior year tax positions 1,820 — 7,880 Reductions related to prior year tax positions (45,305 ) (50 ) — Additions related to current year tax positions 70,444 139,473 11,829 Balance at the end of the year $ 209,443 $ 182,484 $ 43,061
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, 2015 2014 Total unrecognized tax benefits balance $ 209,443 $ 182,484 Amounts netted against related deferred tax assets (208,307 ) (181,786 ) Unrecognized tax benefits recorded on consolidated balance sheets $ 1,136 $ 698

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Minimum Commitments Under Non-Cancelable Capital and Operating Lease Agreements	A summary of gross and net lease commitments as of December 31, 2015 is as follows (in thousands): Operating Capital Leases Leases Years ending December 31, 2016 $ 148,001 $ 93,001 2017 155,213 49,454 2018 149,298 10,739 2019 116,764 592 2020 105,086 — Thereafter 243,788 — $ 918,150 153,786 Less: Amounts representing interest 5,925 Total capital lease obligation 147,861 Less: Short-term portion 88,166 Long-term portion $ 59,695

Segment Information and Opera39

Segment Information and Operations by Geographic Area (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 2014 2013 Revenue by services: Advertising services $ 1,994,036 $ 1,255,688 $ 594,546 Data licensing and other 223,996 147,314 70,344 Total revenue $ 2,218,032 $ 1,403,002 $ 664,890 Year Ended December 31, 2015 2014 2013 Revenue by geographic area: United States $ 1,443,240 $ 945,720 $ 492,320 International 774,792 457,282 172,570 Total revenue $ 2,218,032 $ 1,403,002 $ 664,890
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, 2015 2014 Property and equipment, net: United States $ 683,176 $ 523,810 International 52,123 33,209 Total property and equipment, net $ 735,299 $ 557,019

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Capital lease obligations included in short-term and long-term	$ 147,900,000	$ 231,300,000
Interest expense in relation to capital lease arrangements.	8,800,000	10,200,000	$ 7,000,000
Interest earned on cash, cash equivalent and marketable securities	9,100,000	1,900,000	700,000
Capitalized interest expenses	5,000,000	0	0
Impairment charges on goodwill	0
Impairment charges on intangible assets	0
Software developing program costs capitalized	$ 92,800,000	79,500,000	35,600,000
Percent likelihood for tax benefit amounts to be realized upon settlement	50.00%
Advertising expense	$ 119,700,000	46,600,000	3,100,000
Cost of Revenue
Significant Accounting Policies [Line Items]
Amortization of capitalized costs	37,800,000	15,200,000	6,700,000
Internal Use Software and Website Development Costs
Significant Accounting Policies [Line Items]
Share-based compensation, capitalized amount	$ 50,300,000	$ 40,800,000	$ 13,600,000
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	$ 3,000,000	$ 2,600,000
Other assets
Significant Accounting Policies [Line Items]
Restricted Cash Balances	$ 31,100,000	$ 28,300,000
Minimum
Significant Accounting Policies [Line Items]
Capital leases term	3 years
Intangible assets, estimated useful lives	1 year
Minimum | Internal Use Software and Website Development Costs
Significant Accounting Policies [Line Items]
Estimated useful life	1 year
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
Employee Stock Options
Significant Accounting Policies [Line Items]
Stock-based compensation expense, dividend yield	0.00%

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2015
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 Fixture | 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 Sh42

Cash, Cash Equivalents and Short-term Investments - Cash, Cash and Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash and cash equivalents:
Cash	$ 300,363	$ 147,848
Cash and cash equivalents	911,471	1,510,724	$ 841,010	$ 203,328
Short-term investments:
Short-term investments	2,583,877	2,111,154
Money Market Funds
Cash and cash equivalents:
Cash and cash equivalents	141,700	882,443
U.S. Government and Agency Securities Including Treasury Bills
Cash and cash equivalents:
Cash and cash equivalents		271,418
Short-term investments:
Short-term investments	1,156,418	1,009,541
Corporate Notes Certificates Of Deposit And Commercial Paper
Cash and cash equivalents:
Cash and cash equivalents	469,408	209,015
Short-term investments:
Short-term investments	$ 1,427,459	$ 1,101,613

Cash, Cash Equivalents and Sh43

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, 2015	Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]
Gross Amortized Costs	$ 2,587,853	$ 2,112,102
Gross Unrealized Gains	27	12
Gross Unrealized Losses	(4,003)	(960)
Aggregated Estimated Fair Value	2,583,877	2,111,154
U.S. Government and Agency Securities Including Treasury Bills
Schedule Of Available For Sale Securities [Line Items]
Gross Amortized Costs	1,158,479	1,009,827
Gross Unrealized Gains	6	8
Gross Unrealized Losses	(2,067)	(294)
Aggregated Estimated Fair Value	1,156,418	1,009,541
Corporate Notes Certificates Of Deposit And Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Gross Amortized Costs	1,429,374	1,102,275
Gross Unrealized Gains	21	4
Gross Unrealized Losses	(1,936)	(666)
Aggregated Estimated Fair Value	$ 1,427,459	$ 1,101,613

Cash, Cash Equivalents and Sh44

Cash, Cash Equivalents and Short-term Investments - Contractual Maturities of Securities Classified as Available-for-Sale (Details) $ in Thousands	Dec. 31, 2015USD ($)
Cash And Cash Equivalents And Marketable Securities [Abstract]
Due within one year	$ 1,912,531
Due after one year through two years	671,346
Total	$ 2,583,877

Cash, Cash Equivalents and Sh45

Cash, Cash Equivalents and Short-term Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Investments Debt And Equity Securities [Abstract]
Securities continuous loss position for 12 months or longer	$ 0	$ 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, 2015	Dec. 31, 2014
Fair Value, Net Asset (Liability) [Abstract]
Short-term investments	$ 2,583,877	$ 2,111,154
Other current assets	6,804
Other current liabilities	3,005
Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Total	3,201,789	3,474,030
Total	3,005
Fair Value, Measurements, Recurring | Agency Securities
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		39,998
Short-term investments	589,297	95,838
Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	141,700	882,443
Fair Value, Measurements, Recurring | Treasury Bills
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		73,525
Short-term investments	29,953	167,575
Fair Value, Measurements, Recurring | US Government Securities
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		157,895
Short-term investments	537,168	746,128
Fair Value, Measurements, Recurring | Corporate Notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		13,684
Short-term investments	693,593	551,604
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	419,110	185,321
Short-term investments	229,965	300,589
Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	50,298	10,010
Short-term investments	503,901	249,420
Fair Value, Measurements, Recurring | Foreign currency forward contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	6,804
Other current liabilities	3,005
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Total	171,653	1,123,543
Level 1 | Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	141,700	882,443
Level 1 | Fair Value, Measurements, Recurring | Treasury Bills
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		73,525
Short-term investments	29,953	167,575
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Net Asset (Liability) [Abstract]
Total	3,030,136	2,350,487
Total	3,005
Level 2 | Fair Value, Measurements, Recurring | Agency Securities
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		39,998
Short-term investments	589,297	95,838
Level 2 | Fair Value, Measurements, Recurring | US Government Securities
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		157,895
Short-term investments	537,168	746,128
Level 2 | Fair Value, Measurements, Recurring | Corporate Notes
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents		13,684
Short-term investments	693,593	551,604
Level 2 | Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	419,110	185,321
Short-term investments	229,965	300,589
Level 2 | Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	50,298	10,010
Short-term investments	503,901	$ 249,420
Level 2 | Fair Value, Measurements, Recurring | Foreign currency forward contracts
Fair Value, Net Asset (Liability) [Abstract]
Other current assets	6,804
Other current liabilities	$ 3,005

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	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 forward contracts outstanding	$ 425,200,000	$ 0
Gains on the foreign currency contracts	400,000
Convertible Notes | Senior Notes Due 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument, principal amount	$ 935,000,000	$ 935,000,000	$ 900,000,000
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	$ 954,000,000	$ 954,000,000	$ 900,000,000
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	$ 797,400,000
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	$ 797,900,000

Fair Value Measurements - Sch48

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

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property and equipment, net
Property and equipment, gross	$ 1,314,009	$ 888,270
Less: Accumulated depreciation and amortization	(578,710)	(331,251)
Property and equipment, net	735,299	557,019
Equipment
Property and equipment, net
Property and equipment, gross	720,421	584,561
Furniture and Leasehold Improvements
Property and equipment, net
Property and equipment, gross	297,274	131,851
Computer Software
Property and equipment, net
Property and equipment, gross	211,241	82,052
Construction in Progress
Property and equipment, net
Property and equipment, gross	$ 85,073	$ 89,806

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property Plant And Equipment [Line Items]
Depreciation expense	$ 257.2	$ 171.6	$ 94.4
Computer Hardware, Networking Equipment and Office Equipment
Property Plant And Equipment [Line Items]
Gross carrying amount of property and equipment	370.3	411.3
Accumulated depreciation of the equipment	226.9	182.4
Depreciation expense	$ 118.7	$ 108.7	$ 70.4

Goodwill and Intangible Asset51

Goodwill and Intangible Assets - Schedule of Goodwill Activities (Details) - USD ($) $ in Thousands	1 Months Ended					12 Months Ended
	May. 31, 2015	May. 31, 2014	Oct. 31, 2013	Feb. 28, 2013	Jan. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill
Beginning balance						$ 622,570	$ 363,477
Foreign currency translation adjustment						(1,029)	(708)
Ending balance						1,122,728	622,570	$ 363,477
Gnip Inc
Goodwill
Acquisition		$ 104,700					104,747
TellApart Inc
Goodwill
Acquisition	$ 395,000					394,989
Other acquisitions
Goodwill
Acquisition						$ 106,198	$ 155,054	$ 8,900
Crashlytics
Goodwill
Acquisition					$ 33,300
Bluefin Labs Inc
Goodwill
Acquisition				$ 60,000
MoPub Inc
Goodwill
Acquisition			$ 192,400

Goodwill and Intangible Asset52

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Finite Lived Intangible Assets [Line Items]
Impairment charges on goodwill	$ 0
Amortization of intangible assets	54,700,000	$ 36,600,000
Fully amortized finite lived intangible assets	$ 19,000,000
Minimum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	1 year
Maximum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	11 years
Patents and Developed Technologies | Minimum
Finite Lived Intangible Assets [Line Items]
Intangible assets, estimated useful lives	1 year
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	6 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 Asset53

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 211,804	$ 140,112
Accumulated Amortization	(70,789)	(35,101)
Net Carrying Value	141,015	105,011
Patents and Developed Technologies
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	132,444	105,052
Accumulated Amortization	(43,991)	(23,165)
Net Carrying Value	88,453	81,887
Publisher and Advertiser Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	75,300	32,000
Accumulated Amortization	(23,803)	(9,831)
Net Carrying Value	51,497	22,169
Assembled Workforce
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	1,960	1,960
Accumulated Amortization	(1,714)	(1,457)
Net Carrying Value	246	503
Other Intangible Assets
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	2,100	1,100
Accumulated Amortization	(1,281)	(648)
Net Carrying Value	$ 819	$ 452

Goodwill and Intangible Asset54

Goodwill and Intangible Assets - Schedule of Estimated Future Amortization Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
2,016	$ 44,009
2,017	29,283
2,018	22,730
2,019	15,136
2,020	12,640
Thereafter	17,217
Net Carrying Value	$ 141,015	$ 105,011

Other Balance Sheet Component55

Other Balance Sheet Components - Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Deferred income tax assets, net		$ 25,882
Prepaid and other	$ 247,750	189,639
Total	$ 247,750	$ 215,521

Other Balance Sheet Component56

Other Balance Sheet Components - Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Accrued compensation	$ 90,906	$ 68,000
Accrued sales and marketing expenses	27,948	25,264
Accrued tax liabilities	25,880	18,380
Deferred revenue	23,674	18,679
Accrued publisher and ad network costs	23,486	27,996
Accrued other	91,898	69,914
Total	$ 283,792	$ 228,233

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) $ in Thousands, shares in Millions	1 Months Ended					12 Months Ended
	May. 31, 2015USD ($)shares	May. 31, 2014USD ($)shares	Oct. 31, 2013USD ($)shares	Feb. 28, 2013USD ($)	Jan. 31, 2013USD ($)	Dec. 31, 2015USD ($)Acquisition	Dec. 31, 2014USD ($)Acquisition	Dec. 31, 2013USD ($)Acquisitionshares
Business Acquisition [Line Items]
Fair value of contingent payment						$ 102,900	$ 97,700	$ 83,100
Unrecognized share-based compensation expense						$ 1,250,000
Acquisition of intangible assets for total purchase price								$ 38,500
Granted, options | shares								2
Revenues								$ 9,600
Loss								42,300
Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives						1 year
Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives						11 years
Developed Technology Rights
Business Acquisition [Line Items]
Acquisition of intangible assets for total purchase price								500
Publisher and Advertiser Relationships | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives						2 years
Publisher and Advertiser Relationships | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives						6 years
Patents
Business Acquisition [Line Items]
Acquisition of intangible assets for total purchase price								36,000
Assembled Workforce
Business Acquisition [Line Items]
Acquisition of intangible assets for total purchase price								$ 2,000
Patents Developed Technology And Assembled Work Force | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives								1 year
Patents Developed Technology And Assembled Work Force | 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 | shares	12.2
Business acquisition, assumed common shares / stock options | shares	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 | shares	1.3
Other acquisitions
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration						$ 58,800	66,900	$ 5,800
Business Combination, Consideration Transferred						118,900	188,100	13,200
Business acquisition, common stock issued						60,100	121,200	7,400
Acquisition purchase price allocated to liability								200
Acquisition purchase price allocated to deferred tax liability						3,400	3,200
Goodwill acquired						$ 106,198	$ 155,054	$ 8,900
Number of businesses acquired | Acquisition						4	8	5
Acquisition purchase price allocated to assets						$ 3,200	$ 6,500
Business acquisition, goodwill expected tax deductible amount						4,100	21,900	$ 7,300
Other acquisitions | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets						$ 12,900	$ 28,100	$ 4,500
Other acquisitions | Developed Technology Rights | Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives						12 months	12 months	24 months
Other acquisitions | Developed Technology Rights | Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful lives						60 months	48 months	36 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		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
Unrecognized share-based compensation expense							$ 16,900	$ 24,500
Gnip Inc
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration		$ 107,300
Business acquisition, common stock issued | shares		0.6
Business acquisition, assumed common shares / stock options | shares		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					$ 104,747
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
Crashlytics
Business Acquisition [Line Items]
Business Combination, Consideration Transferred					$ 38,200
Acquisition purchase price allocated to liability					100
Acquisition purchase price allocated to deferred tax liability					300
Goodwill acquired					33,300
Acquisition purchase price allocated to assets					300
Contingent consideration classified as equity, fair value disclosure					6,700
Crashlytics | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets					$ 5,000
Intangible assets, estimated useful lives					12 months
Bluefin Labs Inc
Business Acquisition [Line Items]
Business Combination, Consideration Transferred				$ 67,300
Acquisition purchase price allocated to liability				1,900
Goodwill acquired				60,000
Acquisition purchase price allocated to assets				1,800
Contingent consideration classified as equity, fair value disclosure				7,900
Bluefin Labs Inc | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets				$ 7,400
Intangible assets, estimated useful lives				18 months
MoPub Inc
Business Acquisition [Line Items]
Business acquisition, common stock issued | shares			11.2
Business Combination, Consideration Transferred			$ 218,800
Account receivables			22,100
Other tangible assets			1,200
Acquisition purchase price allocated to deferred tax liability			5,500
Goodwill acquired			$ 192,400
Acquired of the ownership interest percentage			100.00%
Unvested restricted stock | shares			2
Receive aggregate stock option | shares			1.2
Publisher payments liabilities			$ 22,100
Other liabilities			4,400
Granted, options | shares								1.2
MoPub Inc | Employee Stock Options
Business Acquisition [Line Items]
Equity compensation service period								48 months
MoPub Inc | Developed Technology Rights
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets			$ 12,900
Intangible assets, estimated useful lives			36 months
MoPub Inc | Trade Name
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets			$ 1,100
Intangible assets, estimated useful lives			24 months
MoPub Inc | Publisher and Advertiser Relationships
Business Acquisition [Line Items]
Acquisition purchase price allocated to finite lived intangible assets			$ 21,100
Intangible assets, estimated useful lives			36 months

Convertible Notes - Additional

Convertible Notes - Additional Information (Details) $ / shares in Units, shares in Millions		1 Months Ended	9 Months Ended	12 Months Ended
		Oct. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Dec. 31, 2015USD ($)d$ / shares	Dec. 31, 2014USD ($)$ / sharesshares
Debt Instrument [Line Items]
Amortization of discount on convertible notes				$ 69,185,000	$ 18,823,000
Convertible notes				$ 1,455,095,000	1,376,020,000
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				$ 5,100,000	1,400,000
Accrued coupon interest expense				$ 11,900,000	$ 3,300,000
Conversion Price | $ / shares				$ 77.64
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				$ 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			900,000,000	$ 935,000,000	935,000,000
Proceeds from Issuance of Debt		$ 35,000,000
Initial purchasers' discount	[1]			$ 181,994,000	$ 225,104,000
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				$ 753,006,000	709,896,000
Remaining period for convertible debt				44 months
Convertible Notes | Senior Notes Due 2021
Debt Instrument [Line Items]
Debt instrument, principal amount			$ 900,000,000	$ 954,000,000	954,000,000
Proceeds from Issuance of Debt		$ 54,000,000
Initial purchasers' discount	[1]			$ 251,911,000	$ 287,876,000
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				$ 702,089,000	$ 666,124,000
Remaining period for convertible debt				68 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, 2015	Dec. 31, 2014	Sep. 30, 2014
Principal amounts:
Net carrying amount		$ 1,455,095	$ 1,376,020
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	$ 900,000
Unamortized initial purchasers' discount and debt discount	[1]	(181,994)	(225,104)
Net carrying amount		753,006	709,896
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	$ 900,000
Unamortized initial purchasers' discount and debt discount	[1]	(251,911)	(287,876)
Net carrying amount		702,089	666,124
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, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net loss	$ (521,031)	$ (577,820)	$ (645,323)
Basic shares:
Weighted-average common shares outstanding	670,132	613,944	196,675
Weighted-average restricted stock subject to repurchase	(7,708)	(8,954)	(7,165)
Weighted-average shares used to compute basic net loss per share	662,424	604,990	189,510
Diluted shares:
Weighted-average shares used to compute diluted net loss per share	662,424	604,990	189,510
Net loss per share attributable to common stockholders:
Basic	$ (0.79)	$ (0.96)	$ (3.41)
Diluted	$ (0.79)	$ (0.96)	$ (3.41)

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, 2015	Dec. 31, 2014	Dec. 31, 2013
RSUs
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	43,170	64,135	95,723
Warrants
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	24,329	24,329	117
Stock Options
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	11,177	20,420	42,246
Restricted Common Stock and Others
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from the computation of diluted net income per share	9,146	9,335	12,882

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share Basic [Line Items]
Conversion spread will have a dilutive impact on diluted net income per share of common stock	24,300,000
Exercise price of the warrants	$ 105.28
Convertible Notes
Earnings Per Share Basic [Line Items]
Conversion Price	$ 77.64
Exercise price of the warrants		$ 105.28

Preferred Stock - Additional In

Preferred Stock - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
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 Stockholders64

Common Stock and Stockholders' Equity - Additional Information (Details) - USD ($)	Nov. 07, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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
Income taxes paid		$ 11,101,000	$ 17,053,000	$ 14,637,000
Issuance of common stock upon purchases under employee stock purchase plan, shares		1,500,000	1,900,000
Employee stock purchase plan (ESOP), weighted average purchase price of shares purchased		$ 25.78	$ 22.47
Incremental Share-based compensation cost		$ 0	$ 32,600,000	0
Unrecognized share-based compensation expense		$ 1,250,000,000
Unrecognized share-based compensation expense, weighted average recognition period		2 years 6 months 4 days
Internal Use Software and Website Development Costs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, capitalized amount		$ 50,300,000	40,800,000	$ 13,600,000
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		28,900,000
Common stock, reserved for future issuance		113,100,000
2007 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options and restricted stock units outstanding		23,300,000
Issuance of common stock upon initial public offering, shares		0
2013 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for issuance	11,300,000
Outstanding shares of common stock percentage	1.00%
Company’s common stock at a discount through payroll deductions	15.00%
Lower fair market value of common stock on the first trading day	85.00%
All Acquisitions
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period		48 months		48 months
Restricted Common Stock | All Acquisitions | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period		4 years
Pre Twenty Thirteen Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period		4 years
Income taxes paid			17,100,000
Share-based compensation expense			84,400,000	$ 433,500,000
Accumulated share based compensation				405,900,000
Share-based compensation recognized in subsequent period				27,600,000
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options exercised, intrinsic value		$ 337,200,000	$ 872,800,000	$ 123,700,000
Employee Stock Options | All Acquisitions
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity compensation service period		45 months	48 months
Unrecognized share-based compensation expense		$ 37,200,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of restricted stock units vested		$ 849,800,000	$ 2,020,000,000

Common Stock and Stockholders65

Common Stock and Stockholders' Equity - Summary of Restricted Stock Activity (Details) - Restricted Common Stock shares in Thousands	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Unvested Shares, beginning of period | shares	4,955
Number of Shares, granted | shares	2,467
Number of Shares, vested | shares	(2,534)
Number of Shares, Canceled | shares	(348)
Number of Unvested Shares, end of period | shares	4,540
Weighted Average Grant Date Fair Value Per Share, beginning of period | $ / shares	$ 25.62
Weighted Average Grant Date Fair Value Per Share, Granted | $ / shares	40
Weighted Average Grant Date Fair Value Per Share, Vested | $ / shares	24.31
Weighted Average Grant Date Fair Value Per Share, Canceled | $ / shares	29.34
Weighted Average Grant Date Fair Value Per Share, end of period | $ / shares	$ 33.88

Common Stock and Stockholders66

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, 2015	Dec. 31, 2014
Options Outstanding - Number of Shares
Outstanding at beginning of period	20,420
Options granted and assumed in connection with acquisitions	2,212
Options exercised	(10,992)
Options canceled	(463)
Outstanding at end of period	11,177	20,420
Vested and expected to vest at end of period	10,383
Exercisable at end of period	8,526
Options Outstanding - Weighted-Average Exercise Price Per Share
Outstanding at beginning of period	$ 3.33
Options granted and assumed in connection with acquisitions	12.34
Options exercised	1.58
Options canceled	10.05
Outstanding at end of period	6.55	$ 3.33
Vested and expected to vest at end of period	5.56
Exercisable at end of period	$ 3.49
Options Outstanding - Weighted-Average Remaining Contractual Life
Outstanding	5 years 10 months 10 days	5 years 9 months 11 days
Vested and expected to vest at end of period	5 years 7 months 24 days
Exercisable at end of period	5 years 1 month 17 days
Options Outstanding - Aggregate Intrinsic Value
Outstanding at beginning of period	$ 667,538
Outstanding at end of period	199,576	$ 667,538
Vested and expected to vest at end of period	192,696
Exercisable at end of period	$ 170,483

Common Stock and Stockholders67

Common Stock and Stockholders' Equity - Summary of RSU Activity (Details) - RSUs shares in Thousands	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Unvested Shares, beginning of period | shares	64,135
Number of Shares, granted | shares	18,493
Number of Shares, vested | shares	(24,002)
Number of Shares, Canceled | shares	(15,456)
Number of Unvested Shares, end of period | shares	43,170
Weighted Average Grant Date Fair Value Per Share, beginning of period | $ / shares	$ 29.08
Weighted Average Grant Date Fair Value Per Share, Granted | $ / shares	35.45
Weighted Average Grant Date Fair Value Per Share, Vested | $ / shares	27.58
Weighted Average Grant Date Fair Value Per Share, Canceled | $ / shares	29.60
Weighted Average Grant Date Fair Value Per Share, end of period | $ / shares	$ 32.46

Common Stock and Stockholders68

Common Stock and Stockholders' Equity - Compensation Expense Allocated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 682,118	$ 631,597	$ 600,367
Cost of Revenue
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	40,705	50,536	50,942
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	401,537	360,726	379,913
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	156,904	157,263	114,440
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 82,972	$ 63,072	$ 55,072

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Domestic	$ (201,628)	$ (164,854)	$ (549,397)
Foreign	(331,677)	(413,497)	(97,749)
Loss before income taxes	$ (533,305)	$ (578,351)	$ (647,146)

Income Taxes - Components of Be

Income Taxes - Components of Benefit from Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
State	$ 1,226	$ 720	$ 857
Foreign	14,625	8,358	6,222
Total current provision for income taxes	15,851	9,078	7,079
Deferred:
Federal	(23,208)	(8,972)	(5,412)
State	(852)	(128)	(453)
Foreign	(4,065)	(509)	(3,037)
Total deferred benefit for income taxes	(28,125)	(9,609)	(8,902)
Benefit from income taxes	$ (12,274)	$ (531)	$ (1,823)

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, 2015	Dec. 31, 2014	Dec. 31, 2013
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	(0.10%)	(0.10%)	(0.10%)
Stock-based compensation	(2.90%)	(4.20%)	(2.90%)
Research and development credits	7.20%	25.20%	3.60%
Valuation Allowance	3.10%	(9.40%)	(25.00%)
Nondeductible expenses	(5.60%)	(4.50%)	(3.00%)
Foreign rate differential	(23.70%)	(26.40%)	(5.80%)
Change in tax positions	(10.70%)	(15.90%)	(2.00%)
Other	0.00%	0.40%	0.50%
Effective tax rate	2.30%	0.10%	0.30%

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, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 242,987	$ 230,417
Accruals and reserves	36,133	20,496
Stock-based compensation expense	80,106	89,159
Research and development credits	209,425	168,934
California Enterprise Zone Credit	11,710	10,355
Fixed assets and intangible assets	1,457
Other	7,059	3,145
Total deferred tax assets	588,877	522,506
Valuation allowance	(378,448)	(351,249)
Total deferred tax assets, net of valuation allowance	210,429	171,257
Deferred tax liabilities:
Fixed assets and intangible assets	(174,007)	(132,671)
Convertible notes	(30,002)	(35,133)
Other	(1,577)	(420)
Total deferred tax liabilities	(205,586)	(168,224)
Net deferred tax assets	$ 4,843	$ 3,033

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Deferred tax assets	$ 4,843,000	$ 3,033,000
Undistributed earnings for foreign subsidiaries	82,400,000
Operating loss carryforwards related to excess tax benefit from stock-based compensation	3,350,000,000
Unrecognized tax benefits	209,443,000	182,484,000	$ 43,061,000	$ 23,352,000
Net unrecognized tax benefit included in the deferred and other long-term tax liabilities	1,136,000	$ 698,000
Decrease in net deferred tax assets and the related liability for unrecognized tax benefits	15,800,000
California Enterprise Zone
Income Tax Contingency [Line Items]
Credit carryforwards amount	$ 18,000,000
Credit carryforward, expiration year	2,023
Uncertain Tax Positions
Income Tax Contingency [Line Items]
Significant accrued interest and penalties related to uncertain tax positions	$ 0
Foreign Jurisdictions
Income Tax Contingency [Line Items]
Deferred tax assets	5,200,000
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 3,370,000,000
Operating loss carryforwards, expiration year	2,027
Credit carryforward, expiration start year	2,027
Federal | Research
Income Tax Contingency [Line Items]
Credit carryforwards amount	$ 188,200,000
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 1,340,000,000
Operating loss carryforwards, expiration year	2,016
State | Research
Income Tax Contingency [Line Items]
Credit carryforwards amount	$ 150,600,000

Income Taxes - Schedule of Re74

Income Taxes - Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Balance at the beginning of the year	$ 182,484	$ 43,061	$ 23,352
Additions related to prior year tax positions	1,820		7,880
Reductions related to prior year tax positions	(45,305)	(50)
Additions related to current year tax positions	70,444	139,473	11,829
Balance at the end of the year	$ 209,443	$ 182,484	$ 43,061

Income Taxes - Summary of Remai

Income Taxes - Summary of Remaining Balances Recorded in Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Uncertainties [Abstract]
Total unrecognized tax benefits balance	$ 209,443	$ 182,484	$ 43,061	$ 23,352
Amounts netted against related deferred tax assets	(208,307)	(181,786)
Unrecognized tax benefits recorded on consolidated balance sheets	$ 1,136	$ 698

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	2,016
Expiration year of operating lease, last	2,026
Operating leases, rent expense, net	$ 119,800,000	$ 73,900,000	$ 35,400,000
Non-cancelable commitments	$ 166,300,000
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 Contingencies77

Commitments and Contingencies - Minimum Commitments Under Non-Cancelable Capital and Operating Lease Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Operating Leases Future Minimum Payments Due [Abstract]
2,016	$ 148,001
2,017	155,213
2,018	149,298
2,019	116,764
2,020	105,086
Thereafter	243,788
Total	918,150
Capital Leases Future Minimum Payments Due [Abstract]
2,016	93,001
2,017	49,454
2,018	10,739
2,019	592
2,020	0
Thereafter	0
Total	153,786
Less: Amounts representing interest	5,925
Total capital lease obligation	147,861
Less: Short-term portion	88,166	$ 112,320
Long-term portion	$ 59,695	$ 118,950

Related Party Transactions - Ad

Related Party Transactions - Additional Infomation (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
Contribution cost that will be recorded as treasury stock transaction if approved by the the stockholders		$ 0

Segment Information and Opera79

Segment Information and Operations by Geographic Area - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Revenue	$ 2,218,032	$ 1,403,002	$ 664,890
United States
Revenue:
Revenue	1,443,240	945,720	492,320
International
Revenue:
Revenue	774,792	457,282	172,570
Advertising Services
Revenue:
Revenue	1,994,036	1,255,688	594,546
Data Licensing And Other
Revenue:
Revenue	$ 223,996	$ 147,314	$ 70,344

Segment Information and Opera80

Segment Information and Operations by Geographic Area - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)Country	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 2,218,032	$ 1,403,002	$ 664,890
International
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue	$ 774,792	457,282	172,570
Revenue | United Kingdom
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue		$ 140,300	$ 66,500
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 | United Kingdom
Revenues From External Customers And Long Lived Assets [Line Items]
Concentration risk percentage	10.00%	10.00%	10.00%

Segment Information and Opera81

Segment Information and Operations by Geographic Area - Property and Equipment Net by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property and equipment, net:
Property and equipment, net	$ 735,299	$ 557,019
United States
Property and equipment, net:
Property and equipment, net	683,176	523,810
International
Property and equipment, net:
Property and equipment, net	$ 52,123	$ 33,209

Restructuring Charges - Additio

Restructuring Charges - Additional Information (Details) $ in Millions	1 Months Ended
	Oct. 31, 2015USD ($)
Restructuring And Related Activities [Abstract]
Percentage on employees restructuring and reduction plan	8.00%
Cash expenditures on severance costs	$ 16.1
Restructuring expenses	$ 12.9

Schedule II - Valuation and Q83

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Deferred Tax Assets
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 351,249	$ 227,878	$ 42,175
Charged to Expenses	27,175	155,111	180,691
Charged/Credited to Other Accounts	24	(31,740)	5,012
Balance at End of Year	378,448	351,249	227,878
Allowance for Doubtful Accounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	5,507	2,020	1,280
Additions (Reductions)	5,765	4,632	1,557
Write-off/ Adjustments	(3,151)	(1,145)	(817)
Balance at End of Year	$ 8,121	$ 5,507	$ 2,020