0001086222-19-000241 | 10-Q | XBRL Viewer

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2019	Nov. 05, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	0-27275
Entity Registrant Name	Akamai Technologies, Inc
Entity Central Index Key	0001086222
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3432319
Entity Address, Address Line One	145 Broadway
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	444-3000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock - par value $0.01 per share
Trading Symbol	AKAM
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		161,601,210

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 738,462	$ 1,036,455
Marketable securities	831,749	855,650
Accounts receivable, net of reserves of $1,745 and $1,534 at September 30, 2019, and December 31, 2018, respectively	516,657	479,889
Prepaid expenses and other current assets	167,040	163,360
Total current assets	2,253,908	2,535,354
Marketable securities	734,116	209,066
Property and equipment, net	1,079,914	910,618
Operating lease right-of-use assets	349,155
Acquired intangible assets, net	166,407	168,348
Goodwill	1,583,479	1,487,404
Deferred income tax assets	39,321	34,913
Other assets	151,134	116,067
Total assets	6,357,434	5,461,770
Current liabilities:
Accounts payable	108,187	99,089
Accrued expenses	304,333	328,304
Deferred revenue	98,842	69,083
Convertible senior notes	0	686,552
Operating lease liabilities	86,959
Other current liabilities	4,202	27,681
Total current liabilities	602,523	1,210,709
Deferred revenue	4,526	4,557
Deferred income tax liabilities	21,797	19,624
Convertible senior notes	1,823,448	874,080
Operating lease liabilities	296,750
Other liabilities	106,790	160,940
Total liabilities	2,855,834	2,269,910
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.01 par value; 5,000,000 shares authorized; 700,000 shares designated as Series A Junior Participating Preferred Stock; no shares issued or outstanding	0	0
Common stock, $0.01 par value; 700,000,000 shares authorized; 165,211,770 shares issued and 161,659,502 shares outstanding at September 30, 2019, and 162,904,550 shares issued and outstanding at December 31, 2018	1,652	1,629
Additional paid-in capital	3,919,264	3,670,033
Accumulated other comprehensive loss	(56,424)	(48,912)
Treasury stock, at cost, 3,552,268 shares at September 30, 2019, and no shares at December 31, 2018	(291,788)	0
Accumulated deficit	(71,104)	(430,890)
Total stockholders’ equity	3,501,600	3,191,860
Total liabilities and stockholders’ equity	$ 6,357,434	$ 5,461,770

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Accounts receivable reserve	$ 1,745	$ 1,534
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares designated as Series A Junior Participating Preferred Stock	700,000	700,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	700,000,000	700,000,000
Common stock, shares issued	165,211,770	162,904,550
Common stock, shares outstanding	161,659,502	162,904,550
Treasury stock, shares	3,552,268	0

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 709,912	$ 669,628	$ 2,121,494	$ 2,001,111
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)	246,938	239,246	729,874	709,558
Research and development	64,887	61,049	192,467	185,823
Sales and marketing	122,258	125,323	383,640	379,556
General and administrative	123,216	119,911	366,167	444,502
Amortization of acquired intangible assets	9,624	8,294	28,871	25,019
Restructuring (benefit) charges	(300)	(732)	6,879	14,442
Total costs and operating expenses	566,623	553,091	1,707,898	1,758,900
Income from operations	143,289	116,537	413,596	242,211
Interest income	7,908	9,258	22,953	19,632
Interest expense	(12,127)	(14,566)	(32,689)	(28,620)
Other expense, net	(752)	(459)	(819)	(3,207)
Income before provision for income taxes	138,318	110,770	403,041	230,016
Benefit (provision) for income taxes	960	(3,187)	(42,718)	(25,658)
Loss from equity method investment	(1,388)	0	(1,388)	0
Net income	$ 137,890	$ 107,583	$ 358,935	$ 204,358
Net income per share:
Basic (in dollars per share)	$ 0.85	$ 0.65	$ 2.20	$ 1.21
Diluted (in dollars per share)	$ 0.84	$ 0.64	$ 2.18	$ 1.20
Shares used in per share calculations:
Basic (in shares)	162,445	165,924	163,029	168,763
Diluted (in shares)	164,558	167,900	164,788	170,732

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 137,890	$ 107,583	$ 358,935	$ 204,358
Other comprehensive loss:
Foreign currency translation adjustments	(14,095)	(7,771)	(10,744)	(26,046)
Change in unrealized gain (loss) on investments, net of income tax (provision) benefit of $(52), $(494), $(1,153) and $78 for the three and nine months ended September 30, 2019 and 2018, respectively	155	1,524	3,232	(242)
Other comprehensive loss	(13,940)	(6,247)	(7,512)	(26,288)
Comprehensive income	$ 123,950	$ 101,336	$ 351,423	$ 178,070

- Definition

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

+ References + Details

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Income tax on unrealized gain (loss) on investments	$ (52)	$ (494)	$ (1,153)	$ 78

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 358,935	$ 204,358
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	324,874	318,226
Stock-based compensation	140,262	138,815
Provision for deferred income taxes	24,581	12,906
Amortization of debt discount and issuance costs	30,761	27,844
Restructuring-related software charges	0	2,818
Other non-cash reconciling items, net	3,778	9,360
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(38,144)	(13,611)
Prepaid expenses and other current assets	(11,663)	(2,084)
Accounts payable and accrued expenses	(29,441)	7,921
Deferred revenue	16,714	23,927
Other current liabilities	(21,850)	2,030
Other non-current assets and liabilities	(22,643)	(10,338)
Net cash provided by operating activities	776,164	722,172
Cash flows from investing activities:
Cash paid for acquired businesses, net of cash acquired	(121,409)	(79)
Cash paid for equity method investment	(36,008)	0
Purchases of property and equipment	(268,766)	(143,285)
Capitalization of internal-use software development costs	(159,645)	(145,122)
Purchases of short- and long-term marketable securities	(1,373,563)	(782,086)
Proceeds from sales of short- and long-term marketable securities	547	16,308
Proceeds from maturities of short- and long-term marketable securities	878,779	378,708
Other non-current assets and liabilities	1,895	(2,678)
Net cash used in investing activities	(1,078,170)	(678,234)
Cash flows from financing activities:
Proceeds from the issuance of convertible senior notes	1,135,629	1,132,185
Proceeds from the issuance of warrants	185,150	119,945
Purchase of note hedge related to convertible senior notes	(312,225)	(261,740)
Repayment of convertible senior notes	(690,000)	0
Proceeds related to the issuance of common stock under stock plans	43,204	52,497
Employee taxes paid related to net share settlement of stock-based awards	(61,116)	(52,145)
Repurchases of common stock	(291,788)	(625,925)
Other non-current assets and liabilities	(1,558)	(5,085)
Net cash provided by financing activities	7,296	359,732
Effects of exchange rate changes on cash, cash equivalents and restricted cash	(2,650)	(11,528)
Net (decrease) increase in cash, cash equivalents and restricted cash	(297,360)	392,142
Cash, cash equivalents and restricted cash at beginning of period	1,036,987	314,429
Cash, cash equivalents and restricted cash at end of period	739,627	706,571
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds received of $2,746 and $17,286 for the nine months ended September 30, 2019 and 2018, respectively	65,896	32,485
Cash paid for operating lease liabilities	107,478
Non-cash activities:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	87,207
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	64,982	54,414
Capitalization of stock-based compensation	$ 27,352	$ 25,676

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Statement of Cash Flows [Abstract]
Proceeds from income tax refunds	$ 2,746	$ 17,286
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	738,462	705,407
Restricted cash	1,165	1,164
Cash, cash equivalents and restricted cash at end of period	$ 739,627	$ 706,571

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017		169,893,324
Beginning Balance at Dec. 31, 2017	$ 3,362,469	$ 1,699	$ 4,073,362	$ 0	$ (21,930)	$ (690,662)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment to accumulated deficit related to adoption of new accounting pronouncement	(38,601)					(38,601)
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes (in shares)		1,797,241
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes	(44,601)	$ 18	(44,619)
Issuance of common stock under employee stock purchase plan (in shares)		543,520
Issuance of common stock under employee stock purchase plan	25,768	$ 5	25,763
Stock-based compensation	164,310		164,310
Equity component of convertible senior notes, net of issuance costs	275,836		275,836
Issuance of warrants related to convertible senior notes	119,945		119,945
Purchase of note hedge related to convertible senior notes	(261,740)		(261,740)
Repurchases of common stock (in shares)		(8,347,366)
Repurchases of common stock	(625,925)			(625,925)
Net income	204,358					204,358
Foreign currency translation adjustments					(26,047)
Change in unrealized gain on investments, net of tax	(242)				(241)
Ending balance (in shares) at Sep. 30, 2018		163,886,719
Ending Balance at Sep. 30, 2018	3,155,531	$ 1,722	4,352,857	(625,925)	(48,218)	(524,905)
Beginning balance (in shares) at Jun. 30, 2018		169,311,093
Beginning Balance at Jun. 30, 2018	3,445,278	$ 1,718	4,303,531	(185,512)	(41,971)	(632,488)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes (in shares)		470,224
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes	(6,087)	$ 4	(6,091)
Stock-based compensation	55,417		55,417
Repurchases of common stock (in shares)		(5,894,598)
Repurchases of common stock	(440,413)			(440,413)
Net income	107,583					107,583
Foreign currency translation adjustments	(7,771)				(7,771)
Change in unrealized gain on investments, net of tax	1,524				1,524
Ending balance (in shares) at Sep. 30, 2018		163,886,719
Ending Balance at Sep. 30, 2018	3,155,531	$ 1,722	4,352,857	(625,925)	(48,218)	(524,905)
Beginning balance (in shares) at Dec. 31, 2018		162,904,550
Beginning Balance at Dec. 31, 2018	3,191,860	$ 1,629	3,670,033	0	(48,912)	(430,890)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment to accumulated deficit related to adoption of new accounting pronouncement	851					851
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes (in shares)		1,833,758
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes	(59,635)	$ 18	(59,653)
Issuance of common stock under employee stock purchase plan (in shares)		473,462
Issuance of common stock under employee stock purchase plan	27,669	$ 5	27,664
Stock-based compensation	167,475		167,475
Equity component of convertible senior notes, net of issuance costs	240,820		240,820
Issuance of warrants related to convertible senior notes	185,150		185,150
Purchase of note hedge related to convertible senior notes	(312,225)		(312,225)
Repurchases of common stock (in shares)		(3,552,268)
Repurchases of common stock	(291,788)			(291,788)
Net income	358,935					358,935
Foreign currency translation adjustments	(10,744)				(10,744)
Change in unrealized gain on investments, net of tax	3,232				3,232
Ending balance (in shares) at Sep. 30, 2019		161,659,502
Ending Balance at Sep. 30, 2019	3,501,600	$ 1,652	3,919,264	(291,788)	(56,424)	(71,104)
Beginning balance (in shares) at Jun. 30, 2019		163,359,091
Beginning Balance at Jun. 30, 2019	3,394,764	$ 1,649	3,760,840	(116,247)	(42,484)	(208,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes (in shares)		305,367
Issuance of common stock upon the exercise of stock options and vesting of restricted and deferred stock units, net of shares withheld for employee taxes	(10,724)	$ 3	(10,727)
Stock-based compensation	55,406		55,406
Equity component of convertible senior notes, net of issuance costs	240,820		240,820
Issuance of warrants related to convertible senior notes	185,150		185,150
Purchase of note hedge related to convertible senior notes	(312,225)		(312,225)
Repurchases of common stock (in shares)		(2,004,956)
Repurchases of common stock	(175,541)			(175,541)
Net income	137,890					137,890
Foreign currency translation adjustments	(14,095)				(14,095)
Change in unrealized gain on investments, net of tax	155				155
Ending balance (in shares) at Sep. 30, 2019		161,659,502
Ending Balance at Sep. 30, 2019	$ 3,501,600	$ 1,652	$ 3,919,264	$ (291,788)	$ (56,424)	$ (71,104)

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Statement of Stockholders' Equity [Abstract]
Deferred tax for convertible senior notes	$ 23,170	$ 23,170	$ 4,971
Issuance costs for convertible senior notes	$ 2,880	$ 2,880	$ 4,418

Nature of Business and Basis of Presentation	9 Months Ended
Nature of Business and Basis of Presentation	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Nature of Business and Basis of Presentation Akamai Technologies, Inc. (the “Company”) provides solutions for delivering, optimizing and securing content and business applications over the Internet. Its globally-distributed platform comprises more than 200,000 servers across more than 130 countries. The Company was incorporated in Delaware in 1998 and is headquartered in Cambridge, Massachusetts. The Company currently operates in one industry segment: providing cloud services for delivering, optimizing and securing content and business applications over the Internet. The accompanying interim consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information. These financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in the accompanying financial statements. Certain information and footnote disclosures normally included in the Company’s annual audited consolidated financial statements and accompanying notes have been condensed in, or omitted from, these interim financial statements. Accordingly, the unaudited consolidated financial statements included herein should be read in conjunction with the audited consolidated financial statements and accompanying notes included in the Company’s annual report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission on February 28, 2019. The results of operations presented in this quarterly report on Form 10-Q are not necessarily indicative of the results of operations that may be expected for any future periods. In the opinion of management, these unaudited consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, that are necessary for a fair statement of the results of all interim periods reported herein. Newly-Adopted Accounting Pronouncements Leases In February 2016, the Financial Accounting Standards Board ("FASB") issued guidance that requires companies to present assets and liabilities arising from leases on the consolidated balance sheet. The updated standard aims to increase transparency and comparability among organizations by requiring lessees to recognize right-of-use (“ROU”) assets and lease liabilities on the balance sheet and disclose key information about leasing arrangements. The Company adopted this standard on January 1, 2019 on a modified retrospective basis by applying the new standard to its lease portfolio as of January 1, 2019, while continuing to apply legacy guidance in the comparative periods. The Company elected to use the package of practical expedients available under the transition provisions of the guidance, which allows companies to not reassess prior conclusions related to contracts containing leases, lease classification and capitalization of initial direct costs. The Company also elected not to apply the hindsight practical expedient related to its lease transactions. Adoption of the standard required the Company to record ROU assets and lease liabilities for its operating leases related to real estate and co-location arrangements. The operating leases resulted in the recognition of ROU assets and lease liabilities of $362.2 million and $394.1 million, respectively, as of January 1, 2019. The adoption of the standard also resulted in elimination of deferred rent liabilities of $31.7 million, as of January 1, 2019, that are now recorded as a reduction of the ROU asset. The standard did not have an impact on the Company’s results of operations or cash flows. Stranded Tax Effects Resulting from U.S. Tax Cuts and Jobs Act In February 2018, the FASB issued guidance that allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act ("TCJA") that was enacted in 2017. This guidance was effective for the Company on January 1, 2019. The adoption of this new accounting guidance resulted in the reclassification of $0.9 million of income tax benefits resulting from the TCJA from accumulated other comprehensive loss to accumulated deficit. The adoption of this new accounting guidance did not have an impact on the Company's results of operations or cash flows.

Significant Accounting Policies Update	9 Months Ended
Significant Accounting Policies Update	Sep. 30, 2019
Accounting Policies [Abstract]
Significant Accounting Policies Update	Significant Accounting Policies Update The Company's significant accounting policies are detailed in Note 2 of its annual report on Form 10-K for the year ended December 31, 2018. However, the following policies have been updated as of January 1, 2019. Property and Equipment Property and equipment are recorded at cost, net of accumulated depreciation and amortization. Property and equipment generally includes purchases of items with a per-unit value greater than $1,000 and a useful life greater than one year. Depreciation and amortization are computed on a straight-line basis over the estimated useful lives of the assets. The Company periodically reviews the estimated useful lives of property and equipment. Changes to the estimated useful lives are recorded prospectively from the date of the change. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in income from operations. The Company has implemented software and hardware initiatives to manage its global network more efficiently and, as a result, the expected average useful life of its network assets, primarily servers, increased from four years to five years, effective January 1, 2019. These changes decreased depreciation expense by $7.8 million and $24.5 million for the three and nine months ended September 30, 2019, respectively, and increased net income by $6.4 million and $20.3 million for the three and nine months ended September 30, 2019, respectively, or $0.04 and $0.12 per share, for the three and nine months ended September 30, 2019, respectively. Operating Leases The Company enters into operating leases for real estate assets related to office space and co-location assets related to space or racks at co-location facilities and related equipment for its servers and other networking equipment. The Company determines if an arrangement contains a lease at the inception of a contract by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration and the right to obtain the economic benefits from the use of the identified asset. Upon commencement of a lease, the Company records an ROU asset that represents the Company’s right to use the underlying asset for the lease term and a lease liability that represents an obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. Lease payments are discounted at the lease commencement date using the rate implicit in the lease unless that rate is not readily determinable. As most of the Company’s leases do not provide an implicit rate, an incremental borrowing rate has been applied based on the Company's credit-adjusted risk-free rate. The incremental borrowing rate at January 1, 2019 (the date the new lease standard was adopted) was used to calculate the present value of the Company’s lease portfolio as of that date. The Company often enters into contracts that contain both lease and non-lease components. Real estate non-lease components include real estate taxes, insurance, maintenance, parking and other operating costs. Co-location non-lease components include utilities and other operating costs. As of January 1, 2019, the Company includes both lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities based on actual usage, are not included in the measurement of ROU assets and lease liabilities but are expensed when the event determining the amount of variable consideration to be paid occurs. The Company’s lease terms often include renewal options and, particularly in the case of co-location arrangements, may include evergreen provisions. The Company’s ROU assets and lease liabilities generally do not include the options to extend, or terminate, unless it is reasonably certain that the Company will exercise these options. The Company has elected to exclude leases for certain networking equipment with terms of 12 months or less from its ROU assets and lease liabilities on its consolidated balance sheet. Lease expense is recognized on a straight-line basis over the lease term. Equity Method Investments The Company accounts for equity investments in which it has significant influence, but not a controlling financial interest, using the equity method of accounting. Under the equity method of accounting, investments are initially recorded at cost, less impairment, and subsequently adjusted to recognize the Company’s share of earnings or losses. In February 2019, the Company and Mitsubishi UFJ Financial Group ("MUFG") announced the establishment of a joint venture, the Global Open Network, Inc. ("GO-NET"), and their plans to offer a new blockchain-based online payment network. The Company's 20% stake in GO-NET is accounted for using the equity method. As of September 30, 2019, the Company's $36.0 million investment is included in other assets on the consolidated balance sheet. The Company recorded a loss of $1.4 million during the three months ended September 30, 2019 which reflects its share of the losses incurred by GO-NET during the period. Recent Accounting Pronouncements In June 2016, the FASB issued guidance that introduces a new methodology for accounting for credit losses on financial instruments, including available-for-sale debt securities. The guidance establishes a new "expected loss model" that requires entities to estimate current expected credit losses on financial instruments by using all practical and relevant information. Any expected credit losses are to be reflected as allowances rather than reductions in the amortized cost of available-for-sale debt securities. This guidance will be effective for the Company on January 1, 2020. The Company does not expect application of this guidance to have a material impact on its consolidated financial statements. In August 2018, the FASB issued guidance that changes fair value measurement disclosure requirements. This guidance will be effective for the Company on January 1, 2020. The Company is evaluating the impact the update will have on its disclosures. In August 2018, the FASB issued guidance that addresses a customer’s accounting for implementation costs incurred in a cloud computing arrangement that is a service contract. The guidance aligns the accounting for costs incurred to implement a cloud computing arrangement that is a service arrangement with the guidance for capitalizing costs associated with developing or obtaining internal-use software. This guidance will be effective for the Company on January 1, 2020. The Company is evaluating the potential impact of adopting this new accounting guidance on its consolidated financial statements.

Fair Value Measurements

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following is a summary of available-for-sale marketable securities held as of September 30, 2019 and December 31, 2018 (in thousands):



			Gross Unrealized							Classification on Balance Sheet
	Amortized Cost		Gains		Losses			Aggregate Fair Value		Short-Term Marketable Securities		Long-Term Marketable Securities
As of September 30, 2019
Commercial paper	$	78,454	$	20	$	(38	)	$	78,436	$	78,436	$	—
Corporate bonds	1,286,133		1,491		(878		)	1,286,746		638,604		648,142
U.S. government agency obligations	186,836		16		(196		)	186,656		114,468		72,188
	$	1,551,423	$	1,527	$	(1,112	)	$	1,551,838	$	831,508	$	720,330

As of December 31, 2018
Certificates of deposit	$	40,000	$	—	$	(7	)	$	39,993	$	39,993	$	—
Commercial paper	282,996		—		(50		)	282,946		282,946		—
Corporate bonds	685,653		1		(4,309		)	681,345		482,088		199,257
U.S. government agency obligations	50,876		—		(404		)	50,472		50,472		—
	$	1,059,525	$	1	$	(4,770	)	$	1,054,756	$	855,499	$	199,257

The Company offers certain eligible employees the ability to participate in a non-qualified deferred compensation plan. The mutual funds held by the Company that are associated with this plan are classified as restricted trading securities. These securities are not included in the available-for-sale securities table above but are included in marketable securities in the consolidated balance sheets.

Unrealized gains and unrealized temporary losses on investments classified as available-for-sale are included within accumulated other comprehensive loss in the consolidated balance sheets. Upon realization, those amounts are reclassified from

accumulated other comprehensive loss to interest income in the consolidated statements of income. As of September 30, 2019, the Company held for investment corporate and government bonds with a fair value of $125.4 million, which are classified as available-for-sale marketable securities and have been in a continuous unrealized loss position for more than 12 months. The unrealized losses of $0.1 million related to these corporate and government bonds are included in accumulated other comprehensive income as of September 30, 2019. The unrealized losses are attributable to changes in interest rates. Based on the evaluation of available evidence, the Company does not believe any unrealized losses represent other than temporary impairments.

The following table details the fair value measurements within the fair value hierarchy of the Company’s financial assets and liabilities as of September 30, 2019 and December 31, 2018 (in thousands):



	Total Fair Value			Fair Value Measurements at Reporting Date Using
	Total Fair Value			Level 1		Level 2		Level 3
As of September 30, 2019
Cash Equivalents and Marketable Securities:
Money market funds	$	4,000		$	4,000	$	—	$	—
Commercial paper	78,436			—		78,436		—
Corporate bonds	1,286,746			—		1,286,746		—
U.S. government agency obligations	186,656			—		186,656		—
Mutual funds	14,027			14,027		—		—
	$	1,569,865		$	18,027	$	1,551,838	$	—

As of December 31, 2018
Cash Equivalents and Marketable Securities:
Money market funds	$	380,260		$	380,260	$	—	$	—
Certificates of deposit	39,993			39,993		—		—
Commercial paper	282,946			—		282,946		—
Corporate bonds	681,345			—		681,345		—
U.S. government agency obligations	50,472			—		50,472		—
Mutual funds	10,016			10,016		—		—
	$	1,445,032		$	430,269	$	1,014,763	$	—

Liabilities:
Contingent consideration related to a completed acquisition	$	(6,300	)	$	—	$	—	$	(6,300	)

As of September 30, 2019 and December 31, 2018, the Company grouped certificates of deposit, money market funds and mutual funds using a Level 1 valuation because market prices for such investments are readily available in active markets. As of September 30, 2019 and December 31, 2018, the Company grouped commercial paper, corporate bonds and U.S. government agency obligations using a Level 2 valuation because quoted prices for identical or similar assets are available in markets that are inactive. The Company did not have any transfers of assets between Level 1, Level 2 or Level 3 of the fair value measurement hierarchy during the nine months ended September 30, 2019.

When developing fair value estimates, the Company maximizes the use of observable inputs and minimizes the use of unobservable inputs. When available, the Company uses quoted market prices to measure fair value. The valuation technique used to measure fair value for the Company's Level 1 and Level 2 assets is a market approach, using prices and other relevant information generated by market transactions involving identical or comparable assets. If market prices are not available, the fair value measurement is based on models that primarily use market-based parameters including yield curves, volatilities, credit ratings and currency rates. In certain cases where market rate assumptions are not available, the Company is required to make judgments about assumptions market participants would use to estimate the fair value of a financial instrument.

The valuation technique used to measure fair value of the Company's Level 3 liabilities, which consist of contingent consideration related to the acquisition of Cyberfend, Inc. in 2016, was primarily an income-based approach. The significant

unobservable input used in the fair value measurement of the contingent consideration was the likelihood of achieving certain post-closing financial results.

Contractual maturities of the Company’s available-for-sale marketable securities held as of September 30, 2019 and December 31, 2018 were as follows (in thousands):



	September 30, 2019		December 31, 2018
Due in 1 year or less	$	831,508	$	855,499
Due after 1 year through 3 years	720,330		199,257
	$	1,551,838	$	1,054,756

The following table reflects the activity for the Company’s liabilities measured at fair value using Level 3 inputs during the nine months ended September 30, 2019 (in thousands):



	Other Liabilities: Contingent Consideration Obligation
Balance as of January 1, 2019	$	(6,300	)
Cash paid upon achievement of milestone	6,300
Balance as of September 30, 2019	$	—

Accounts Receivable

9 Months Ended

Sep. 30, 2019

Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]

Accounts Receivable

Net accounts receivable consisted of the following as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019			December 31, 2018
Trade accounts receivable	$	357,050		$	337,445
Unbilled accounts receivable	161,352			143,978
Gross accounts receivable	518,402			481,423
Allowance for doubtful accounts and other reserves	(1,745		)	(1,534		)
Accounts receivable, net	$	516,657		$	479,889

Incremental Costs to Obtain a Contract with a Customer

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Incremental Costs to Obtain a Contract with a Customer

The following table summarizes the deferred costs associated with obtaining customer contracts, specifically commission and incentive payments, as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019		December 31, 2018
Deferred costs included in prepaid and other current assets	$	41,085	$	41,955
Deferred costs included in other assets	21,625		26,338
Total deferred costs	$	62,710	$	68,293

During the three and nine months ended September 30, 2019, the Company recognized $10.9 million and $32.5 million, respectively, of amortization expense related to deferred commissions. During the three and nine months ended September 30, 2018, the Company recognized $11.2 million and $32.9 million, respectively, of amortization expense related to deferred commissions. Amortization expense related to deferred commissions is primarily included in sales and marketing expense in the consolidated statements of income.

Revenue from Contracts with Customers

The Company sells its solutions through a sales force located both domestically and abroad. Revenue derived from operations outside of the U.S. is determined based on the country in which the sale originated. Other than the U.S., no single country accounted for 10% or more of the Company’s total revenue for any reported period. The following table summarizes revenue by geography included in the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
U.S.	$	413,116	$	412,573	$	1,248,175	$	1,249,041
International	296,796		257,055		873,319		752,070
Total revenue	$	709,912	$	669,628	$	2,121,494	$	2,001,111

While the Company sells its solutions through a geographically dispersed sales force, it manages its customer relationships in two divisions: the Web Division and the Media and Carrier Division. Customers are assigned to a division for relationship management purposes according to their predominant purchasing activity; however, customers may purchase solutions managed by the other division as well. As of January 1, 2019, the Company reassigned some of its customers from the Media and Carrier Division to the Web Division and revised historical results in order to reflect the most recent categorization and to provide a comparable view for all periods presented. As the purchasing patterns and required account expertise of customers change over time, the Company may reassign a customer's division from one to another. The following table summarizes revenue by division included in the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
Web Division	$	390,223	$	357,255	$	1,146,872	$	1,062,376
Media and Carrier Division	319,689		312,373		974,622		938,735
Total revenue	$	709,912	$	669,628	$	2,121,494	$	2,001,111

Most content delivery and security services sold by the Company represent obligations that are satisfied over time as the customer simultaneously receives and consumes the services provided. Accordingly, the majority of the Company's revenue is recognized over time, generally ratably over the term of the arrangement due to consistent monthly traffic commitments that expire each period. A small percentage of the Company's services are satisfied at a point in time, such as one-time professional services contracts, integration services and most license sales where the primary obligation is delivery of the license at the start of the term. In these cases, revenue is recognized at a point in time of delivery or satisfaction of the performance obligation.

During the nine months ended September 30, 2019 and 2018, the Company recognized $51.0 million and $64.3 million of revenue that was included in deferred revenue as of December 31, 2018 and 2017, respectively.

As of September 30, 2019, the aggregate amount of remaining performance obligations from contracts with customers was $2.3 billion. The Company expects to recognize more than 70% of its remaining performance obligations as revenue over the next 12 months, with the remaining recognized thereafter. Remaining performance obligations represent the amount of the transaction price under contracts with customers that are attributable to performance obligations that are unsatisfied or partially satisfied at the reporting date. This consists of future committed revenue for monthly, quarterly or annual periods within current contracts with customers, as well as deferred revenue arising from consideration invoiced in prior periods for which the related performance obligations have not been satisfied. It excludes estimates of variable consideration such as usage-based contracts with no committed contract as well as anticipated renewed contracts.

Goodwill and Acquired Intangible Assets

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Acquired Intangible Assets

The change in the carrying amount of goodwill for the nine months ended September 30, 2019 was as follows (in thousands):



Balance as of January 1, 2019	$	1,487,404
Acquisition of Janrain, Inc.	99,685
Foreign currency translation	(3,610		)
Balance as of September 30, 2019	$	1,583,479

The Company tests goodwill for impairment at least annually. Through the date the consolidated financial statements were issued, no triggering events had occurred that would indicate a potential impairment exists.

Acquired intangible assets that are subject to amortization consisted of the following as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019							December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Completed technology	$	154,091	$	(95,861	)	$	58,230	$	145,091	$	(81,587	)	$	63,504
Customer-related intangible assets	263,410		(158,562		)	104,848		245,710		(144,786		)	100,924
Non-compete agreements	730		(467		)	263		700		(306		)	394
Trademarks and trade names	7,400		(4,334		)	3,066		7,200		(3,674		)	3,526
Acquired license rights	490		(490		)	—		490		(490		)	—
Total	$	426,121	$	(259,714	)	$	166,407	$	399,191	$	(230,843	)	$	168,348

Aggregate expense related to amortization of acquired intangible assets for the three and nine months ended September 30, 2019 was $9.6 million and $28.9 million, respectively. Aggregate expense related to amortization of acquired intangible assets for the three and nine months ended September 30, 2018 was $8.3 million and $25.0 million, respectively. Based on the Company’s acquired intangible assets as of September 30, 2019, aggregate expense related to amortization of acquired intangible assets is expected to be $9.6 million for the remainder of 2019, and $36.9 million, $31.9 million, $26.2 million and $20.3 million for 2020, 2021, 2022 and 2023, respectively.

Business Combinations

9 Months Ended

Sep. 30, 2019

Business Combinations [Abstract]

Business Combinations

Acquisition-related costs during the nine months ended September 30, 2019 were $1.2 million and are included in general and administrative expense in the consolidated statements of income. Pro forma results of operations for the acquisition completed during the nine months ended September 30, 2019 have not been presented because the effects of the acquisition were not material to the Company's consolidated financial results. Revenue and earnings of the acquired company since the date of the acquisition that are included in the Company's consolidated statements of income are also not presented separately because they are not material.

ChameleonX

In October 2019, the Company agreed to acquire ChameleonX Ltd., an Israel-based company with a solution designed to detect when a website contains or links to malware that causes end user data to be compromised, for approximately $15.0 million in cash. The acquisition is expected to further strengthen the Company's industry leading security portfolio. The acquisition is expected to close in the fourth quarter of 2019.

Exceda

In November 2019, the Company acquired Exceda, a leading provider of CDN and web security services, and the Company's largest channel partner in Latin America, for approximately $33.0 million in cash. The acquisition is expected to enable the Company to expand its Latin America business more quickly, better enable existing and new partners and improve experiences for more customers.

Janrain

In January 2019, the Company acquired Janrain, Inc. ("Janrain"), a provider of customer identity and access management solutions, for $123.6 million in cash. The allocation of the purchase price has not been finalized as of the date of the filing of these financial statements. The Company plans to incorporate the Janrain technology into Akamai's Intelligent Edge Platform.

The following table presents the preliminary allocation of the purchase price for Janrain (in thousands):



Total purchase consideration	$	123,632

Allocation of the purchase consideration:
Cash	$	2,223
Accounts receivable	7,318
Prepaid expenses and other current assets	838
Identifiable intangible assets	26,930
Goodwill	99,685
Deferred tax assets	5,124
Other assets	87
Total assets acquired	142,205
Accounts payable	(1,641		)
Accrued expenses	(2,596		)
Deferred revenue	(14,336		)
Total liabilities assumed	(18,573		)
Net assets acquired	$	123,632

The value of the goodwill can be attributed to a number of business factors, including a trained technical and sales workforce and cost synergies expected to be realized. The total amount of goodwill related to the acquisition of Janrain expected to be deductible for tax purposes is $42.5 million.

The following were the identifiable intangible assets acquired and their respective weighted average useful lives (in thousands, except years):



	Gross Carrying Amount		Weighted Average Useful Life (in years)
Completed technologies	$	9,000	3.0
Customer-related intangible assets	17,700		6.0
Trademarks	200		0.8
Non-compete agreements	30		1.0
Total	$	26,930

The total weighted average amortization period for the intangible assets acquired from Janrain is 5.0 years. The intangible assets are being amortized based upon the pattern in which the economic benefits of the intangible assets are being utilized.

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters In April 2018, as part of the resolution of multiple existing lawsuits between Limelight Networks, Inc. ("Limelight") and the Company, including in the U.S. District Court for the Eastern District of Virginia and in the U.S. District Court for the District of Massachusetts, the Company and Limelight entered into an agreement to settle the cases and request that the U.S. Patent Trial and Appeal Board terminate certain proceedings related to patents at issue in the litigation. The Company recorded a $14.9 million charge in the third quarter of 2018, which is included in general and administrative expenses in the consolidated statement of income for the nine months ended September 30, 2018, related to this settlement.

Debt

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Debt

Convertible Notes – Due 2027

In August 2019, the Company issued $1,150.0 million in par value of convertible senior notes due 2027 (the "2027 Notes"). The 2027 Notes are senior unsecured obligations of the Company, bear regular interest of 0.375%, payable semi-annually in arrears on March 1 and September 1 of each year, beginning on March 1, 2020, and mature on September 1, 2027, unless repurchased or converted in accordance with their terms prior to maturity.

At their option, holders may convert their 2027 Notes prior to the close of business on the business day immediately preceding May 1, 2027, only under the following circumstances:

•

during any calendar quarter commencing after the calendar quarter ended December 31, 2019 (and only during such calendar quarter), if the last reported sale price of the Company's common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day;


•	during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of 2027 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate on each such trading day; or


•	upon the occurrence of specified corporate events.

On or after May 1, 2027, holders may convert all or any portion of their 2027 Notes at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date.

Upon conversion, the Company, at its election, may pay or deliver to holders cash, shares of the Company's common stock or a combination of cash and shares of the Company's common stock. The initial conversion rate is 8.6073 shares of the Company's common stock per $1,000 principal amount, which is equivalent to an initial conversion price of approximately $116.18 per share, subject to adjustments in certain events, and represents a potential conversion into 9.9 million shares.

In accounting for the issuance of the 2027 Notes, the Company separated the 2027 Notes into liability and equity components. The carrying cost of the liability component was calculated by measuring the fair value of a similar debt obligation that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the 2027 Notes. The difference between the principal amount of the 2027 Notes and the proceeds allocated to the liability component (“debt discount”) is amortized to interest expense using the effective interest method over the term of the 2027 Notes. The equity component is recorded in additional paid-in capital in the consolidated balance sheet and will not be remeasured as long as it continues to meet the conditions for equity classification.

In accounting for the transaction costs related to the issuance of the 2027 Notes, the Company allocated the total transaction costs incurred to the liability and equity components based on their relative values. Transaction costs attributable to the liability component are being amortized to interest expense over the term of the 2027 Notes, and transaction costs attributable to the equity component are netted against the equity component of the 2027 Notes in stockholders’ equity.

The 2027 Notes consisted of the following components as of September 30, 2019 (in thousands):



	September 30, 2019
Liability component:
Principal	$	1,150,000
Less: debt discount and issuance costs, net of amortization	(229,454		)
Net carrying amount	$	920,546

Equity component:	$	220,529

The estimated fair value of the 2027 Notes at September 30, 2019 was $1,172.8 million. The fair value was determined based on the quoted price of the 2027 Notes in an inactive market on the last trading day of the reporting period and has been classified as Level 2 within the fair value hierarchy. Based on the closing price of the Company's common stock of $91.38 on September 30, 2019, the value of the 2027 Notes if converted to common stock was less than the principal amount of $1,150.0 million.

The Company used $100.0 million of the proceeds from the offering to repurchase shares of its common stock, concurrent with the issuance of the 2027 Notes. The repurchase was made in accordance with a share repurchase program previously approved by the Board of Directors. Additionally, $127.1 million of the proceeds was used for the net cost of convertible note hedge and warrant transactions. The net proceeds are intended to be used for working capital, share repurchases, potential acquisitions and strategic transactions and other corporate purposes.

Note Hedge

To minimize the impact of potential dilution upon conversion of the 2027 Notes, the Company entered into convertible note hedge transactions with respect to its common stock in August 2019. The Company paid $312.2 million for the note hedge transactions. The note hedge transactions cover approximately 9.9 million shares of the Company’s common stock at a strike price that corresponds to the initial conversion price of the 2027 Notes, also subject to adjustment, and are exercisable upon conversion of the 2027 Notes. The note hedge transactions are intended to reduce dilution in the event of conversion of the 2027 Notes.

Warrants

Separately, in August 2019, the Company entered into warrant transactions, whereby the Company sold warrants to acquire, subject to anti-dilution adjustments, up to 9.9 million shares of the Company’s common stock at a strike price of approximately $178.74 per share. The Company received aggregate proceeds of $185.2 million from the sale of the warrants. The convertible note hedge and warrant transactions will generally have the effect of increasing the conversion price of the 2027 Notes to approximately $178.74 per share.

Convertible Notes – Due 2025

In May 2018, the Company issued $1,150.0 million in par value of convertible senior notes due 2025 (the "2025 Notes"). The 2025 Notes are senior unsecured obligations of the Company, bear regular interest of 0.125%, payable semi-annually on May 1 and November 1 of each year, and mature on May 1, 2025, unless repurchased or converted prior to maturity.

At their option, holders may convert their 2025 Notes prior to the close of business on the business day immediately preceding January 1, 2025, only under the following circumstances:

•

during any calendar quarter commencing after the calendar quarter ended June 30, 2018 (and only during such calendar quarter), if the last reported sale price of the Company's common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day;


•	during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of 2025 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate on each such trading day; or


•	upon the occurrence of specified corporate events.

On or after January 1, 2025, holders may convert all or any portion of their 2025 Notes at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date.

Upon conversion, the Company, at its election, may pay or deliver to holders cash, shares of the Company's common stock or a combination of cash and shares of the Company's common stock. The initial conversion rate is 10.5150 shares of the Company's common stock per $1,000 principal amount, which is equivalent to an initial conversion price of approximately $95.10 per share, subject to adjustments in certain events, and represents a potential conversion into 12.1 million shares.

In accounting for the issuance of the 2025 Notes, the Company separated the 2025 Notes into liability and equity components. The carrying cost of the liability component was calculated by measuring the fair value of a similar debt obligation that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the 2025 Notes. The difference between the principal amount of the 2025 Notes and the proceeds allocated to the liability component (“debt discount”) is amortized to interest expense using the effective interest method over the term of the 2025 Notes. The equity component is recorded in additional paid-in capital in the consolidated balance sheet and will not be remeasured as long as it continues to meet the conditions for equity classification.

In accounting for the transaction costs related to the issuance of the 2025 Notes, the Company allocated the total transaction costs incurred to the liability and equity components based on their relative values. Transaction costs attributable to the liability component are being amortized to interest expense over the term of the 2025 Notes, and transaction costs attributable to the equity component are netted against the equity component of the 2025 Notes in stockholders’ equity.

The 2025 Notes consisted of the following components as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019			December 31, 2018
Liability component:
Principal	$	1,150,000		$	1,150,000
Less: debt discount and issuance costs, net of amortization	(247,098		)	(275,920		)
Net carrying amount	$	902,902		$	874,080

Equity component:	$	285,225		$	285,225

The estimated fair value of the 2025 Notes at September 30, 2019 was $1,319.6 million. The fair value was determined based on the quoted price of the 2025 Notes in an inactive market on the last trading day of the reporting period and has been classified as Level 2 within the fair value hierarchy. Based on the closing price of the Company's common stock of $91.38 on September 30, 2019, the value of the 2025 Notes if converted to common stock was less than the principal amount of $1,150.0 million.

The Company used $46.2 million of the proceeds from the offering to repurchase shares of its common stock, concurrent with the issuance of the 2025 Notes. The repurchase was made in accordance with a share repurchase program previously approved by the Board of Directors. Additionally, $141.8 million of the proceeds was used for the net cost of convertible note hedge and warrant transactions. The Company also used a portion of the net proceeds to repay at maturity the $690.0 million in par value of convertible senior notes due 2019.

Note Hedge

To minimize the impact of potential dilution upon conversion of the 2025 Notes, the Company entered into convertible note hedge transactions with respect to its common stock in May 2018. The Company paid $261.7 million for the note hedge transactions. The note hedge transactions cover approximately 12.1 million shares of the Company’s common stock at a strike price that corresponds to the initial conversion price of the 2025 Notes, also subject to adjustment, and are exercisable upon conversion of the 2025 Notes. The note hedge transactions are intended to reduce dilution in the event of conversion of the 2025 Notes.

Warrants

Separately, in May 2018, the Company entered into warrant transactions, whereby the Company sold warrants to acquire, subject to anti-dilution adjustments, up to 12.1 million shares of the Company’s common stock at a strike price of approximately $149.18 per share. The Company received aggregate proceeds of $119.9 million from the sale of the warrants. The convertible note hedge and warrant transactions will generally have the effect of increasing the conversion price of the 2025 Notes to approximately $149.18 per share.

Convertible Notes – Due 2019

In February 2014, the Company issued $690.0 million in par value of convertible senior notes due 2019 (the "2019 Notes"). The 2019 Notes were senior unsecured obligations of the Company and did not bear regular interest. The 2019 Notes matured and were repaid in full on February 15, 2019 as no repurchases or conversions occurred prior to maturity. For further information, see Note 11 to the consolidated financial statements included in the Company’s annual report on Form 10-K for the year ended December 31, 2018.

Revolving Credit Facility

In May 2018, the Company entered into a $500.0 million five-year, revolving credit agreement (the “Credit Agreement”). Borrowings under the Credit Agreement may be used to finance working capital needs and for general corporate purposes. The Credit Agreement provides for an initial $500.0 million in revolving loans. Under specified circumstances, the facility can be increased to up to $1.0 billion in aggregate principal amount. The Credit Agreement expires in May 2023.

Borrowings under the Credit Agreement bear interest, at the Company's option, at a base rate plus a spread of 0.00% to 0.25% or an adjusted LIBOR rate plus a spread of 0.875% to 1.25%, in each case with such spread being determined based on the Company's consolidated leverage ratio specified in the Credit Agreement. Regardless of what amounts, if any, are outstanding under the Credit Agreement, the Company is also obligated to pay an ongoing commitment fee on undrawn amounts at a rate of 0.075% to 0.15%, with such rate being based on the Company's consolidated leverage ratio specified in the Credit Agreement.

The Credit Agreement contains customary representations and warranties, affirmative and negative covenants and events of default. Principal covenants include a maximum consolidated leverage ratio and a minimum consolidated interest coverage ratio. There were no outstanding borrowings under the Credit Agreement as of September 30, 2019.

Interest Expense

The 2027 Notes bear interest at a fixed rate of 0.375%. The interest is payable semi-annually on March 1 and September 1 of each year, commencing in March 2020. The 2027 Notes have an effective interest rate of 3.1% attributable to the conversion feature. The 2025 Notes bear interest at a fixed rate of 0.125%. The interest is payable semi-annually on May 1 and November 1 of each year, commencing in November 2018. The 2025 Notes have an effective interest rate of 4.26% attributable to the conversion feature. The 2019 Notes did not bear regular interest, but had an effective interest rate of 3.2% attributable to the conversion feature. The Company is also obligated to pay ongoing commitment fees under the terms of the Credit Agreement. The following table sets forth total interest expense included in the consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2019			2018			2019			2018
Amortization of debt discount and issuance costs	$	12,982		$	15,295		$	35,657		$	31,045
Coupon interest payable on 2025 Notes	359			359			1,077			514
Coupon interest payable on 2027 Notes	479			—			479			—
Revolving credit facility contractual interest expense	156			122			372			261
Capitalization of interest expense	(1,849		)	(1,210		)	(4,896		)	(3,200		)
Total interest expense	$	12,127		$	14,566		$	32,689		$	28,620

Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Leases

The following table is a summary of the Company’s operating lease costs for the three and nine months ended September 30, 2019 (in thousands):



	For the Three Months Ended September 30, 2019								For the Nine Months Ended September 30, 2019
	Real Estate Arrangements			Co-location Arrangements		Total			Real Estate Arrangements			Co-location Arrangements		Total
Operating lease cost	$	14,517		$	23,142	$	37,659		$	43,506		$	70,082	$	113,588
Short-term lease cost	26			3,509		3,535			231			10,697		10,928
Variable lease cost	3,617			7,053		10,670			10,655			16,769		27,424
Sublease income	(839		)	—		(839		)	(2,791		)	—		(2,791		)
Total operating lease costs	$	17,321		$	33,704	$	51,025		$	51,601		$	97,548	$	149,149

Lease costs for real estate arrangements are included in general and administrative expenses in the consolidated statements of income. Lease costs for co-location arrangements are primarily included in cost of revenue.

At September 30, 2019, the real estate arrangements weighted average remaining lease term and weighted average discount rate for operating leases were 10.0 years and 4.1%, respectively. At September 30, 2019, the co-location arrangements weighted average remaining lease term and weighted average discount rate for operating leases were 3.3 years and 2.3%, respectively.

Maturities of operating lease liabilities as of September 30, 2019 were as follows (in thousands):



	Real Estate Arrangements		Co-location Arrangements
Remainder of 2019	$	10,975	$	27,688
2020	49,206		29,454
2021	45,094		9,789
2022	41,090		5,767
2023	39,245		3,944
Thereafter	200,317		10,158
Total lease payments	385,927		86,800
Less: imputed interest	84,087		4,931
Total lease liabilities	$	301,840	$	81,869

As of September 30, 2019, the Company has additional operating leases, primarily for real estate facilities, that have not yet commenced of $553.0 million. The majority of these operating leases will commence in late 2019 and have a term of 15 years.

The minimum aggregate future obligations under non-cancelable operating leases, including real estate and co-location arrangements, and bandwidth commitments as of December 31, 2018 were as follows (in thousands):



	Real Estate Arrangements		Bandwidth and Co-location Arrangements
2019	$	54,561	$	138,777
2020	78,683		24,420
2021	75,991		8,463
2022	72,579		5,233
2023	70,101		2,156
Thereafter	599,339		3,709
Total	$	951,254	$	182,758

Restructuring

9 Months Ended

Sep. 30, 2019

Restructuring and Related Activities [Abstract]

Restructuring

During the fourth quarter of 2018, management committed to an action to restructure certain parts of the Company to re-balance investments with the goal of improving long-term growth and scale. As a result, certain headcount reductions were necessary and certain capitalized internal-use software charges were realized for software not yet placed into service that will not be completed and implemented due to this action. The Company has incurred restructuring charges of $19.0 million as part of this action, of which $6.7 million was recognized during the nine months ended September 30, 2019. The Company does not expect significant additional restructuring charges related to this action.

During the fourth quarter of 2017, management committed to an action to restructure certain parts of the Company with the intent of shifting focus to more critical areas of the business and away from products that have not seen expected commercial success. The restructuring was also intended to facilitate cost efficiencies and savings. As part of the cost efficiency and savings plans, certain headcount and facility reductions were made. The Company has incurred restructuring charges of $62.6 million as part of this action. There were insignificant charges related to these actions during the nine months ended September 30, 2019, and no additional charges are expected.

The Company also recognized restructuring charges for redundant employees, facilities and contracts associated with the Janrain acquisition completed in 2019.

The following table summarizes the activity of the Company's restructuring accrual during the nine months ended September 30, 2019 (in thousands):



	Employee Severance and Related Benefits			Software Charges			Excess Facilities, Contract Terminations and Other			Total
Balance as of January 1, 2019	$	10,508		$	198		$	275		$	10,981
Costs incurred	6,825			—			54			6,879
Cash disbursements	(16,839		)	(99		)	(262		)	(17,200		)
Balance as of September 30, 2019	$	494		$	99		$	67		$	660

Stockholders' Equity

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Stockholders' Equity

Stockholders’ Equity

Share Repurchase Program

Effective November 2018, the Board authorized a $1.1 billion repurchase program through December 2021. During the three and nine months ended September 30, 2019, the Company repurchased 2.0 million and 3.6 million shares of its common stock, respectively, for $175.5 million and $291.8 million, respectively. The Company's goals for the share repurchase programs are to offset the dilution created by its employee equity compensation programs and provide the flexibility to return capital to shareholders as business and market conditions warrant.

Stock-Based Compensation

The following table summarizes stock-based compensation included in the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2019			2018			2019			2018
Cost of revenue	$	5,555		$	5,494		$	16,917		$	16,343
Research and development	12,842			11,249			36,943			32,684
Sales and marketing	15,593			16,835			46,384			49,543
General and administrative	12,825			13,054			40,018			40,245
Total stock-based compensation	46,815			46,632			140,262			138,815
Provision for income taxes	(14,867		)	(7,802		)	(41,658		)	(37,692		)
Total stock-based compensation, net of income taxes	$	31,948		$	38,830		$	98,604		$	101,123

In addition to the amounts of stock-based compensation reported in the table above, the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 include stock-based compensation reflected as a component of amortization of capitalized internal-use software of $7.5 million and $22.9 million, respectively, before taxes, and for the three and nine months ended September 30, 2018 include stock-based compensation reflected as a component of amortization of capitalized internal-use software of $6.6 million and $18.1 million, respectively, before taxes.

Accumulated Other Comprehensive Loss

9 Months Ended

Sep. 30, 2019

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive Loss

The following table summarizes the changes in accumulated other comprehensive loss, net of tax, which is reported as a component of stockholders' equity, for the nine months ended September 30, 2019 (in thousands):



	Foreign Currency Translation			Net Unrealized Gains on Investments		Total
Balance as of January 1, 2019	$	(51,904	)	$	2,992	$	(48,912	)
Other comprehensive (loss) income	(10,744		)	3,232		(7,512		)
Balance as of September 30, 2019	$	(62,648	)	$	6,224	$	(56,424	)

Amounts reclassified from accumulated other comprehensive loss to net income were insignificant for the nine months ended September 30, 2019.

Revenue from Contracts with Customers

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Revenue from Contracts with Customers

Incremental Costs to Obtain a Contract with a Customer



	September 30, 2019		December 31, 2018
Deferred costs included in prepaid and other current assets	$	41,085	$	41,955
Deferred costs included in other assets	21,625		26,338
Total deferred costs	$	62,710	$	68,293

Revenue from Contracts with Customers



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
U.S.	$	413,116	$	412,573	$	1,248,175	$	1,249,041
International	296,796		257,055		873,319		752,070
Total revenue	$	709,912	$	669,628	$	2,121,494	$	2,001,111



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
Web Division	$	390,223	$	357,255	$	1,146,872	$	1,062,376
Media and Carrier Division	319,689		312,373		974,622		938,735
Total revenue	$	709,912	$	669,628	$	2,121,494	$	2,001,111

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective income tax rate is based on estimated income for the year, the estimated composition of the income in different jurisdictions and discrete adjustments, if any, in the applicable quarterly periods. Potential discrete adjustments include tax charges or benefits related to stock-based compensation, changes in tax legislation, settlements of tax audits or assessments, uncertain tax positions and acquisitions, among other items. The Company is currently under audit in multiple jurisdictions and, in certain cases, is involved in litigation related to adverse audit determinations. In the second quarter of 2018, the Company filed an appeal with the Massachusetts Appellate Tax Board contesting the adverse audit findings related to certain tax benefits and exemptions. The Company has determined that it is more-likely-than-not that it will prevail, and no reserve has been recorded related to these controversies. Over the next 12 months, the Company’s current assumptions and positions could change based on audit determinations and other events impacting its analysis. Such events, if resolved unfavorably, could significantly impact the Company’s effective income tax rate and results of operations. The Company has estimated that an adverse ruling related to its Massachusetts controversy could ultimately result in an income tax charge of approximately $15.0 million. The Company’s effective income tax rate was 10.6% and 11.2% for the nine months ended September 30, 2019 and 2018, respectively. The lower effective tax rate for the nine months ended September 30, 2019, is primarily due to the release of certain tax reserves related to the expiration of local statutes of limitations, which was partially offset by an increase in the valuation allowance recorded against deferred tax assets related to state tax credits in which it is more likely than not that such credits will expire prior to utilization. For the nine months ended September 30, 2019, the effective income tax rate was lower than the federal statutory tax rate due to the release of certain tax reserves related to the expiration of local statutes of limitations, foreign income taxed at lower rates, the excess tax benefit related to stock-based compensation and the benefit of U.S. federal, state and foreign research and development credits. These amounts were partially offset by the valuation allowance recorded against deferred tax assets related to state tax credits, non-deductible executive compensation, state taxes and an intercompany sale of intellectual property. For the nine months ended September 30, 2018, the effective income tax rate was lower than the federal statutory tax rate due to foreign income taxed at lower rates, the excess tax benefit related to stock-based compensation, a decrease in the provisional amount of the one-time transition tax that was recorded in the fourth quarter of 2017, the release of certain tax reserves related to the expiration of local statutes of limitations and the benefit of U.S. federal, state and foreign research and development credits. These amounts were partially offset by the U.S. federal taxes on Global Intangible Low-Taxed Income and an intercompany sale of intellectual property. Valuation allowances will be recognized on deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be utilized. In measuring deferred tax assets, the Company considers all available evidence, both positive and negative, to determine whether a valuation allowance is needed. In the third quarter of 2019, the Company recorded an additional $11.2 million valuation allowance against deferred tax assets related to state tax credits in which it is more likely than not that such credits will expire prior to utilization.

Net Income per Share

9 Months Ended

Sep. 30, 2019

Earnings Per Share Reconciliation [Abstract]

Net Income per Share

Basic net income per share is computed using the weighted average number of common shares outstanding during the applicable period. Diluted net income per share is computed using the weighted average number of common shares outstanding during the period, plus the dilutive effect of potential common stock. Potential common stock consists of shares issuable pursuant to stock options, restricted stock units ("RSUs"), deferred stock units ("DSUs"), convertible senior notes and warrants issued by the Company. The dilutive effect of outstanding awards and convertible securities is reflected in diluted earnings per share by application of the treasury stock method.

The following table sets forth the components used in the computation of basic and diluted net income per share for the three and nine months ended September 30, 2019 and 2018 (in thousands, except per share data):



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
Numerator:
Net income	$	137,890	$	107,583	$	358,935	$	204,358
Denominator:
Shares used for basic net income per share	162,445		165,924		163,029		168,763
Effect of dilutive securities:
Stock options	36		80		59		158
RSUs and DSUs	2,077		1,896		1,700		1,811
Convertible senior notes	—		—		—		—
Warrants related to issuance of convertible senior notes	—		—		—		—
Shares used for diluted net income per share	164,558		167,900		164,788		170,732
Basic net income per share	$	0.85	$	0.65	$	2.20	$	1.21
Diluted net income per share	$	0.84	$	0.64	$	2.18	$	1.20

For the three and nine months ended September 30, 2019 and 2018, certain potential outstanding common shares from stock options, service-based RSUs, convertible notes and warrants were excluded from the computation of diluted net income per share because the effect of including these items was anti-dilutive. Additionally, certain performance-based RSUs were excluded from the computation of diluted net income per share because the underlying performance conditions for such RSUs had not been met as of these dates. The number of potentially outstanding common shares excluded from the computation of diluted net income per share for the three and nine months ended September 30, 2019 and 2018 are as follows (in thousands):



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
	2019	2018	2019	2018
Service-based RSUs	139	185	959	1,068
Performance-based RSUs	1,484	1,515	1,484	1,520
Convertible senior notes	21,991	19,797	21,991	19,797
Warrants related to issuance of convertible senior notes	21,991	19,797	21,991	19,797
Total shares excluded from computation	45,605	41,294	46,425	42,182

Significant Accounting Policies Update (Policies)	9 Months Ended
Significant Accounting Policies Update (Policies)	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Accounting	The accompanying interim consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information. These financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in the accompanying financial statements. Certain information and footnote disclosures normally included in the Company’s annual audited consolidated financial statements and accompanying notes have been condensed in, or omitted from, these interim financial statements. Accordingly, the unaudited consolidated financial statements included herein should be read in conjunction with the audited consolidated financial statements and accompanying notes included in the Company’s annual report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission on February 28, 2019. The results of operations presented in this quarterly report on Form 10-Q are not necessarily indicative of the results of operations that may be expected for any future periods. In the opinion of management, these unaudited consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, that are necessary for a fair statement of the results of all interim periods reported herein.
Newly-Adopted and Recent Accounting Pronouncements	Newly-Adopted Accounting Pronouncements Leases In February 2016, the Financial Accounting Standards Board ("FASB") issued guidance that requires companies to present assets and liabilities arising from leases on the consolidated balance sheet. The updated standard aims to increase transparency and comparability among organizations by requiring lessees to recognize right-of-use (“ROU”) assets and lease liabilities on the balance sheet and disclose key information about leasing arrangements. The Company adopted this standard on January 1, 2019 on a modified retrospective basis by applying the new standard to its lease portfolio as of January 1, 2019, while continuing to apply legacy guidance in the comparative periods. The Company elected to use the package of practical expedients available under the transition provisions of the guidance, which allows companies to not reassess prior conclusions related to contracts containing leases, lease classification and capitalization of initial direct costs. The Company also elected not to apply the hindsight practical expedient related to its lease transactions. Adoption of the standard required the Company to record ROU assets and lease liabilities for its operating leases related to real estate and co-location arrangements. The operating leases resulted in the recognition of ROU assets and lease liabilities of $362.2 million and $394.1 million, respectively, as of January 1, 2019. The adoption of the standard also resulted in elimination of deferred rent liabilities of $31.7 million, as of January 1, 2019, that are now recorded as a reduction of the ROU asset. The standard did not have an impact on the Company’s results of operations or cash flows. Stranded Tax Effects Resulting from U.S. Tax Cuts and Jobs Act In February 2018, the FASB issued guidance that allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act ("TCJA") that was enacted in 2017. This guidance was effective for the Company on January 1, 2019. The adoption of this new accounting guidance resulted in the reclassification of $0.9 million of income tax benefits resulting from the TCJA from accumulated other comprehensive loss to accumulated deficit. The adoption of this new accounting guidance did not have an impact on the Company's results of operations or cash flows. Recent Accounting Pronouncements In June 2016, the FASB issued guidance that introduces a new methodology for accounting for credit losses on financial instruments, including available-for-sale debt securities. The guidance establishes a new "expected loss model" that requires entities to estimate current expected credit losses on financial instruments by using all practical and relevant information. Any expected credit losses are to be reflected as allowances rather than reductions in the amortized cost of available-for-sale debt securities. This guidance will be effective for the Company on January 1, 2020. The Company does not expect application of this guidance to have a material impact on its consolidated financial statements. In August 2018, the FASB issued guidance that changes fair value measurement disclosure requirements. This guidance will be effective for the Company on January 1, 2020. The Company is evaluating the impact the update will have on its disclosures. In August 2018, the FASB issued guidance that addresses a customer’s accounting for implementation costs incurred in a cloud computing arrangement that is a service contract. The guidance aligns the accounting for costs incurred to implement a cloud computing arrangement that is a service arrangement with the guidance for capitalizing costs associated with developing or obtaining internal-use software. This guidance will be effective for the Company on January 1, 2020. The Company is evaluating the potential impact of adopting this new accounting guidance on its consolidated financial statements.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost, net of accumulated depreciation and amortization. Property and equipment generally includes purchases of items with a per-unit value greater than $1,000 and a useful life greater than one year. Depreciation and amortization are computed on a straight-line basis over the estimated useful lives of the assets. The Company periodically reviews the estimated useful lives of property and equipment. Changes to the estimated useful lives are recorded prospectively from the date of the change. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in income from operations.
Operating Leases	Operating Leases The Company enters into operating leases for real estate assets related to office space and co-location assets related to space or racks at co-location facilities and related equipment for its servers and other networking equipment. The Company determines if an arrangement contains a lease at the inception of a contract by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration and the right to obtain the economic benefits from the use of the identified asset. Upon commencement of a lease, the Company records an ROU asset that represents the Company’s right to use the underlying asset for the lease term and a lease liability that represents an obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. Lease payments are discounted at the lease commencement date using the rate implicit in the lease unless that rate is not readily determinable. As most of the Company’s leases do not provide an implicit rate, an incremental borrowing rate has been applied based on the Company's credit-adjusted risk-free rate. The incremental borrowing rate at January 1, 2019 (the date the new lease standard was adopted) was used to calculate the present value of the Company’s lease portfolio as of that date. The Company often enters into contracts that contain both lease and non-lease components. Real estate non-lease components include real estate taxes, insurance, maintenance, parking and other operating costs. Co-location non-lease components include utilities and other operating costs. As of January 1, 2019, the Company includes both lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities based on actual usage, are not included in the measurement of ROU assets and lease liabilities but are expensed when the event determining the amount of variable consideration to be paid occurs. The Company’s lease terms often include renewal options and, particularly in the case of co-location arrangements, may include evergreen provisions. The Company’s ROU assets and lease liabilities generally do not include the options to extend, or terminate, unless it is reasonably certain that the Company will exercise these options. The Company has elected to exclude leases for certain networking equipment with terms of 12 months or less from its ROU assets and lease liabilities on its consolidated balance sheet. Lease expense is recognized on a straight-line basis over the lease term.
Equity Method Investments	Equity Method Investments The Company accounts for equity investments in which it has significant influence, but not a controlling financial interest, using the equity method of accounting. Under the equity method of accounting, investments are initially recorded at cost, less impairment, and subsequently adjusted to recognize the Company’s share of earnings or losses.

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following is a summary of available-for-sale marketable securities held as of September 30, 2019 and December 31, 2018 (in thousands):



			Gross Unrealized							Classification on Balance Sheet
	Amortized Cost		Gains		Losses			Aggregate Fair Value		Short-Term Marketable Securities		Long-Term Marketable Securities
As of September 30, 2019
Commercial paper	$	78,454	$	20	$	(38	)	$	78,436	$	78,436	$	—
Corporate bonds	1,286,133		1,491		(878		)	1,286,746		638,604		648,142
U.S. government agency obligations	186,836		16		(196		)	186,656		114,468		72,188
	$	1,551,423	$	1,527	$	(1,112	)	$	1,551,838	$	831,508	$	720,330

As of December 31, 2018
Certificates of deposit	$	40,000	$	—	$	(7	)	$	39,993	$	39,993	$	—
Commercial paper	282,996		—		(50		)	282,946		282,946		—
Corporate bonds	685,653		1		(4,309		)	681,345		482,088		199,257
U.S. government agency obligations	50,876		—		(404		)	50,472		50,472		—
	$	1,059,525	$	1	$	(4,770	)	$	1,054,756	$	855,499	$	199,257

Schedule of Fair Value Measurement



	Total Fair Value			Fair Value Measurements at Reporting Date Using
	Total Fair Value			Level 1		Level 2		Level 3
As of September 30, 2019
Cash Equivalents and Marketable Securities:
Money market funds	$	4,000		$	4,000	$	—	$	—
Commercial paper	78,436			—		78,436		—
Corporate bonds	1,286,746			—		1,286,746		—
U.S. government agency obligations	186,656			—		186,656		—
Mutual funds	14,027			14,027		—		—
	$	1,569,865		$	18,027	$	1,551,838	$	—

As of December 31, 2018
Cash Equivalents and Marketable Securities:
Money market funds	$	380,260		$	380,260	$	—	$	—
Certificates of deposit	39,993			39,993		—		—
Commercial paper	282,946			—		282,946		—
Corporate bonds	681,345			—		681,345		—
U.S. government agency obligations	50,472			—		50,472		—
Mutual funds	10,016			10,016		—		—
	$	1,445,032		$	430,269	$	1,014,763	$	—

Liabilities:
Contingent consideration related to a completed acquisition	$	(6,300	)	$	—	$	—	$	(6,300	)

Schedule of Contractual Maturities of Marketable Securities and Other Investment Related Assets

Contractual maturities of the Company’s available-for-sale marketable securities held as of September 30, 2019 and December 31, 2018 were as follows (in thousands):



	September 30, 2019		December 31, 2018
Due in 1 year or less	$	831,508	$	855,499
Due after 1 year through 3 years	720,330		199,257
	$	1,551,838	$	1,054,756

Schedule of Activity of Major Classes of Assets Measured at Fair Value Using Level 3 Inputs

The following table reflects the activity for the Company’s liabilities measured at fair value using Level 3 inputs during the nine months ended September 30, 2019 (in thousands):



	Other Liabilities: Contingent Consideration Obligation
Balance as of January 1, 2019	$	(6,300	)
Cash paid upon achievement of milestone	6,300
Balance as of September 30, 2019	$	—

Accounts Receivable (Tables)

9 Months Ended

Sep. 30, 2019

Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]

Schedule of Accounts Receivable

Net accounts receivable consisted of the following as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019			December 31, 2018
Trade accounts receivable	$	357,050		$	337,445
Unbilled accounts receivable	161,352			143,978
Gross accounts receivable	518,402			481,423
Allowance for doubtful accounts and other reserves	(1,745		)	(1,534		)
Accounts receivable, net	$	516,657		$	479,889

Incremental Costs to Obtain a Contract with a Customer (Tables)

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Schedule of deferred costs associated with obtaining customer contracts



	September 30, 2019		December 31, 2018
Deferred costs included in prepaid and other current assets	$	41,085	$	41,955
Deferred costs included in other assets	21,625		26,338
Total deferred costs	$	62,710	$	68,293

Goodwill and Acquired Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The change in the carrying amount of goodwill for the nine months ended September 30, 2019 was as follows (in thousands):



Balance as of January 1, 2019	$	1,487,404
Acquisition of Janrain, Inc.	99,685
Foreign currency translation	(3,610		)
Balance as of September 30, 2019	$	1,583,479

Schedule of Acquired Intangible Assets

Acquired intangible assets that are subject to amortization consisted of the following as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019							December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Completed technology	$	154,091	$	(95,861	)	$	58,230	$	145,091	$	(81,587	)	$	63,504
Customer-related intangible assets	263,410		(158,562		)	104,848		245,710		(144,786		)	100,924
Non-compete agreements	730		(467		)	263		700		(306		)	394
Trademarks and trade names	7,400		(4,334		)	3,066		7,200		(3,674		)	3,526
Acquired license rights	490		(490		)	—		490		(490		)	—
Total	$	426,121	$	(259,714	)	$	166,407	$	399,191	$	(230,843	)	$	168,348

The following were the identifiable intangible assets acquired and their respective weighted average useful lives (in thousands, except years):



	Gross Carrying Amount		Weighted Average Useful Life (in years)
Completed technologies	$	9,000	3.0
Customer-related intangible assets	17,700		6.0
Trademarks	200		0.8
Non-compete agreements	30		1.0
Total	$	26,930

Business Combinations (Tables)

9 Months Ended

Sep. 30, 2019

Business Combinations [Abstract]

Schedule of Preliminary Allocation of the Purchase Price

The following table presents the preliminary allocation of the purchase price for Janrain (in thousands):



Total purchase consideration	$	123,632

Allocation of the purchase consideration:
Cash	$	2,223
Accounts receivable	7,318
Prepaid expenses and other current assets	838
Identifiable intangible assets	26,930
Goodwill	99,685
Deferred tax assets	5,124
Other assets	87
Total assets acquired	142,205
Accounts payable	(1,641		)
Accrued expenses	(2,596		)
Deferred revenue	(14,336		)
Total liabilities assumed	(18,573		)
Net assets acquired	$	123,632

Schedule of Acquired Intangible Assets

Acquired intangible assets that are subject to amortization consisted of the following as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019							December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Completed technology	$	154,091	$	(95,861	)	$	58,230	$	145,091	$	(81,587	)	$	63,504
Customer-related intangible assets	263,410		(158,562		)	104,848		245,710		(144,786		)	100,924
Non-compete agreements	730		(467		)	263		700		(306		)	394
Trademarks and trade names	7,400		(4,334		)	3,066		7,200		(3,674		)	3,526
Acquired license rights	490		(490		)	—		490		(490		)	—
Total	$	426,121	$	(259,714	)	$	166,407	$	399,191	$	(230,843	)	$	168,348

The following were the identifiable intangible assets acquired and their respective weighted average useful lives (in thousands, except years):



	Gross Carrying Amount		Weighted Average Useful Life (in years)
Completed technologies	$	9,000	3.0
Customer-related intangible assets	17,700		6.0
Trademarks	200		0.8
Non-compete agreements	30		1.0
Total	$	26,930

Debt (Tables)

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Schedule of Convertible Senior Notes

The 2025 Notes consisted of the following components as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019			December 31, 2018
Liability component:
Principal	$	1,150,000		$	1,150,000
Less: debt discount and issuance costs, net of amortization	(247,098		)	(275,920		)
Net carrying amount	$	902,902		$	874,080

Equity component:	$	285,225		$	285,225

The 2027 Notes consisted of the following components as of September 30, 2019 (in thousands):



	September 30, 2019
Liability component:
Principal	$	1,150,000
Less: debt discount and issuance costs, net of amortization	(229,454		)
Net carrying amount	$	920,546

Equity component:	$	220,529

Schedule of Interest Expense

The following table sets forth total interest expense included in the consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2019			2018			2019			2018
Amortization of debt discount and issuance costs	$	12,982		$	15,295		$	35,657		$	31,045
Coupon interest payable on 2025 Notes	359			359			1,077			514
Coupon interest payable on 2027 Notes	479			—			479			—
Revolving credit facility contractual interest expense	156			122			372			261
Capitalization of interest expense	(1,849		)	(1,210		)	(4,896		)	(3,200		)
Total interest expense	$	12,127		$	14,566		$	32,689		$	28,620

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Components of Lease Expense

The following table is a summary of the Company’s operating lease costs for the three and nine months ended September 30, 2019 (in thousands):



	For the Three Months Ended September 30, 2019								For the Nine Months Ended September 30, 2019
	Real Estate Arrangements			Co-location Arrangements		Total			Real Estate Arrangements			Co-location Arrangements		Total
Operating lease cost	$	14,517		$	23,142	$	37,659		$	43,506		$	70,082	$	113,588
Short-term lease cost	26			3,509		3,535			231			10,697		10,928
Variable lease cost	3,617			7,053		10,670			10,655			16,769		27,424
Sublease income	(839		)	—		(839		)	(2,791		)	—		(2,791		)
Total operating lease costs	$	17,321		$	33,704	$	51,025		$	51,601		$	97,548	$	149,149

Maturities of Operating Lease Liabilities

Maturities of operating lease liabilities as of September 30, 2019 were as follows (in thousands):



	Real Estate Arrangements		Co-location Arrangements
Remainder of 2019	$	10,975	$	27,688
2020	49,206		29,454
2021	45,094		9,789
2022	41,090		5,767
2023	39,245		3,944
Thereafter	200,317		10,158
Total lease payments	385,927		86,800
Less: imputed interest	84,087		4,931
Total lease liabilities	$	301,840	$	81,869

Minimum Aggregate Future Obligations Under Non-Cancelable Leases



	Real Estate Arrangements		Bandwidth and Co-location Arrangements
2019	$	54,561	$	138,777
2020	78,683		24,420
2021	75,991		8,463
2022	72,579		5,233
2023	70,101		2,156
Thereafter	599,339		3,709
Total	$	951,254	$	182,758

Restructuring (Tables)

9 Months Ended

Sep. 30, 2019

Restructuring and Related Activities [Abstract]

Schedule of Restructuring Accrual

The following table summarizes the activity of the Company's restructuring accrual during the nine months ended September 30, 2019 (in thousands):



	Employee Severance and Related Benefits			Software Charges			Excess Facilities, Contract Terminations and Other			Total
Balance as of January 1, 2019	$	10,508		$	198		$	275		$	10,981
Costs incurred	6,825			—			54			6,879
Cash disbursements	(16,839		)	(99		)	(262		)	(17,200		)
Balance as of September 30, 2019	$	494		$	99		$	67		$	660

Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Schedule of Stock-Based Compensation Expense

The following table summarizes stock-based compensation included in the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2019			2018			2019			2018
Cost of revenue	$	5,555		$	5,494		$	16,917		$	16,343
Research and development	12,842			11,249			36,943			32,684
Sales and marketing	15,593			16,835			46,384			49,543
General and administrative	12,825			13,054			40,018			40,245
Total stock-based compensation	46,815			46,632			140,262			138,815
Provision for income taxes	(14,867		)	(7,802		)	(41,658		)	(37,692		)
Total stock-based compensation, net of income taxes	$	31,948		$	38,830		$	98,604		$	101,123

Accumulated Other Comprehensive Loss (Tables)

9 Months Ended

Sep. 30, 2019

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)



	Foreign Currency Translation			Net Unrealized Gains on Investments		Total
Balance as of January 1, 2019	$	(51,904	)	$	2,992	$	(48,912	)
Other comprehensive (loss) income	(10,744		)	3,232		(7,512		)
Balance as of September 30, 2019	$	(62,648	)	$	6,224	$	(56,424	)

Revenue from Contracts with Customers (Tables)

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table summarizes revenue by division included in the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
Web Division	$	390,223	$	357,255	$	1,146,872	$	1,062,376
Media and Carrier Division	319,689		312,373		974,622		938,735
Total revenue	$	709,912	$	669,628	$	2,121,494	$	2,001,111

The following table summarizes revenue by geography included in the Company’s consolidated statements of income for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
U.S.	$	413,116	$	412,573	$	1,248,175	$	1,249,041
International	296,796		257,055		873,319		752,070
Total revenue	$	709,912	$	669,628	$	2,121,494	$	2,001,111

Net Income per Share (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share Reconciliation [Abstract]

Schedule of Components Used in Diluted and Basic Income Per Common Share



	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2019		2018		2019		2018
Numerator:
Net income	$	137,890	$	107,583	$	358,935	$	204,358
Denominator:
Shares used for basic net income per share	162,445		165,924		163,029		168,763
Effect of dilutive securities:
Stock options	36		80		59		158
RSUs and DSUs	2,077		1,896		1,700		1,811
Convertible senior notes	—		—		—		—
Warrants related to issuance of convertible senior notes	—		—		—		—
Shares used for diluted net income per share	164,558		167,900		164,788		170,732
Basic net income per share	$	0.85	$	0.65	$	2.20	$	1.21
Diluted net income per share	$	0.84	$	0.64	$	2.18	$	1.20

Schedule of Shares Excluded from Computation of Diluted Earnings Per Share

The number of potentially outstanding common shares excluded from the computation of diluted net income per share for the three and nine months ended September 30, 2019 and 2018 are as follows (in thousands):



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
	2019	2018	2019	2018
Service-based RSUs	139	185	959	1,068
Performance-based RSUs	1,484	1,515	1,484	1,520
Convertible senior notes	21,991	19,797	21,991	19,797
Warrants related to issuance of convertible senior notes	21,991	19,797	21,991	19,797
Total shares excluded from computation	45,605	41,294	46,425	42,182

Nature of Business and Basis of Presentation (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) segment country server	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of servers (more than) \| server	200,000
Number of countries in which servers are located (more than) \| country	130
Number of industry segments \| segment	1
Operating lease right-of-use assets	$ 349,155
Reclassification into retained earnings	$ (71,104)		$ (430,890)
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 362,200
Total lease liabilities		394,100
Deferred rent liabilities		31,700
Stranded Tax Effects Resulting from U.S. Tax Cuts and Jobs Act
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification into retained earnings		$ 900

Significant Accounting Policies Update (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment per unit value minimum	$ 1,000		$ 1,000
Property and equipment useful life minimum			1 year
Loss from equity method investment	$ 1,388,000	$ 0	$ 1,388,000	$ 0
MUFG
Property, Plant and Equipment [Line Items]
Ownership percent	20.00%		20.00%
Equity method investment	$ 36,000,000.0		$ 36,000,000.0
Loss from equity method investment	1,400,000
Network assets
Property, Plant and Equipment [Line Items]
Useful life			5 years		4 years
Decrease to deprecation expense	7,800,000		$ 24,500,000
Increase to net income	$ 6,400,000		$ 20,300,000
Increase to net income (in dollars per share)	$ 0.04		$ 0.12

Fair Value Measurements - Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,551,423	$ 1,059,525
Gross Unrealized Gains	1,527	1
Gross Unrealized Losses	(1,112)	(4,770)
Aggregate Fair Value	1,551,838	1,054,756
Unrealized losses included in accumulated other comprehensive loss	125,400
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		40,000
Gross Unrealized Gains		0
Gross Unrealized Losses		(7)
Aggregate Fair Value		39,993
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	78,454	282,996
Gross Unrealized Gains	20	0
Gross Unrealized Losses	(38)	(50)
Aggregate Fair Value	78,436	282,946
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,286,133	685,653
Gross Unrealized Gains	1,491	1
Gross Unrealized Losses	(878)	(4,309)
Aggregate Fair Value	1,286,746	681,345
Available-for-sale marketable securities, continuous unrealized loss position for more than 12 months	(100)
U.S. government agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	186,836	50,876
Gross Unrealized Gains	16	0
Gross Unrealized Losses	(196)	(404)
Aggregate Fair Value	186,656	50,472
Short-Term Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	831,508	855,499
Short-Term Marketable Securities \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value		39,993
Short-Term Marketable Securities \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	78,436	282,946
Short-Term Marketable Securities \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	638,604	482,088
Short-Term Marketable Securities \| U.S. government agency obligations
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	114,468	50,472
Long-Term Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	720,330	199,257
Long-Term Marketable Securities \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value		0
Long-Term Marketable Securities \| Commercial paper
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	0	0
Long-Term Marketable Securities \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	648,142	199,257
Long-Term Marketable Securities \| U.S. government agency obligations
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	$ 72,188	$ 0

Fair Value Measurements - Schedule of Fair Value Measurement (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 1,551,838	$ 1,054,756
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value		39,993
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	78,436	282,946
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	1,286,746	681,345
U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	186,656	50,472
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities	18,027	430,269
Contingent consideration related to a completed acquisition		0
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	4,000	380,260
Level 1 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value		39,993
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 1 \| U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 1 \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	14,027	10,016
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities	1,551,838	1,014,763
Contingent consideration related to a completed acquisition		0
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Level 2 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value		0
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	78,436	282,946
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	1,286,746	681,345
Level 2 \| U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	186,656	50,472
Level 2 \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities	0	0
Contingent consideration related to a completed acquisition	0	(6,300)
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Level 3 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value		0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 3 \| U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Level 3 \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	0	0
Total Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities	1,569,865	1,445,032
Contingent consideration related to a completed acquisition		(6,300)
Total Fair Value \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	4,000	380,260
Total Fair Value \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value		39,993
Total Fair Value \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	78,436	282,946
Total Fair Value \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	1,286,746	681,345
Total Fair Value \| U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	186,656	50,472
Total Fair Value \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 14,027	$ 10,016

Fair Value Measurements - Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Due in 1 year or less	$ 831,508	$ 855,499
Due after 1 year through 3 years	720,330	199,257
Aggregate Fair Value	$ 1,551,838	$ 1,054,756

Fair Value Measurements - Schedule of Liability Measured at Fair Value using Level 3 Inputs (Details) - Level 3 $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of January 1, 2019	$ (6,300)
Cash paid upon achievement of milestone	6,300
Balance as of September 30, 2019	$ 0

Accounts Receivable - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 518,402	$ 481,423
Allowance for doubtful accounts and other reserves	(1,745)	(1,534)
Accounts receivable, net	516,657	479,889
Unbilled accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	161,352	143,978
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 357,050	$ 337,445

Incremental Costs to Obtain a Contract with a Customer (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Commission and incentive payments
Capitalized Contract Cost [Line Items]
Total deferred costs	$ 62,710		$ 62,710		$ 68,293
Commission and incentive payments \| Deferred costs included in prepaid and other current assets
Capitalized Contract Cost [Line Items]
Total deferred costs	41,085		41,085		41,955
Commission and incentive payments \| Deferred costs included in other assets
Capitalized Contract Cost [Line Items]
Total deferred costs	21,625		21,625		$ 26,338
Deferred commissions
Capitalized Contract Cost [Line Items]
Amortization expense	$ 10,900	$ 11,200	$ 32,500	$ 32,900

Goodwill and Acquired Intangible Assets - Schedule of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Schedule of Goodwill [Roll Forward]
Balance as of January 1, 2019	$ 1,487,404
Acquisition of Janrain, Inc.	99,685
Foreign currency translation	(3,610)
Balance as of September 30, 2019	$ 1,583,479

Goodwill and Acquired Intangible Assets - Schedule of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 426,121	$ 399,191
Accumulated Amortization	(259,714)	(230,843)
Net Carrying Amount	166,407	168,348
Completed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	154,091	145,091
Accumulated Amortization	(95,861)	(81,587)
Net Carrying Amount	58,230	63,504
Customer-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	263,410	245,710
Accumulated Amortization	(158,562)	(144,786)
Net Carrying Amount	104,848	100,924
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	730	700
Accumulated Amortization	(467)	(306)
Net Carrying Amount	263	394
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,400	7,200
Accumulated Amortization	(4,334)	(3,674)
Net Carrying Amount	3,066	3,526
Acquired license rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	490	490
Accumulated Amortization	(490)	(490)
Net Carrying Amount	$ 0	$ 0

Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of acquired intangible assets	$ 9,624	$ 8,294	$ 28,871	$ 25,019
Future amortization expense to be recognized in remainder of 2019	9,600		9,600
Future amortization expense 2020	36,900		36,900
Future amortization expense 2021	31,900		31,900
Future amortization expense 2022	26,200		26,200
Future amortization expense 2023	$ 20,300		$ 20,300

Business Combinations - Narrative (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended	9 Months Ended
	Nov. 08, 2019	Jan. 31, 2019	Dec. 31, 2019	Sep. 30, 2019
ChameleonX \| Forecast
Business Acquisition [Line Items]
Cash consideration			$ 15.0
Exceda \| Subsequent Event
Business Acquisition [Line Items]
Cash consideration	$ 33.0
Janrain, Inc.
Business Acquisition [Line Items]
Cash consideration		$ 123.6
Goodwill expected to be tax deductible		$ 42.5
Weighted average useful life		5 years
General and administrative
Business Acquisition [Line Items]
Acquisition-related costs				$ 1.2

Business Combinations - Schedule of Preliminary Allocation of the Purchase Price (Details) - USD ($) $ in Thousands	1 Months Ended
	Jan. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Allocation of the purchase consideration:
Goodwill		$ 1,583,479	$ 1,487,404
Janrain, Inc.
Business Acquisition [Line Items]
Total purchase consideration	$ 123,632
Allocation of the purchase consideration:
Cash	2,223
Accounts receivable	7,318
Prepaids and other current assets	838
Identifiable intangible assets	26,930
Goodwill	99,685
Deferred tax assets	5,124
Other assets	87
Total assets acquired	142,205
Accounts payable	(1,641)
Accrued liabilities	(2,596)
Deferred revenue	(14,336)
Total liabilities assumed	(18,573)
Net assets acquired	$ 123,632

Business Combinations - Schedule of Acquired Intangible Assets (Details) - Janrain, Inc. $ in Thousands	1 Months Ended
	Jan. 31, 2019 USD ($)
Business Acquisition [Line Items]
Gross carrying amount	$ 26,930
Weighted average useful life	5 years
Completed technology
Business Acquisition [Line Items]
Gross carrying amount	$ 9,000
Weighted average useful life	3 years
Customer-related intangible assets
Business Acquisition [Line Items]
Gross carrying amount	$ 17,700
Weighted average useful life	6 years
Trademarks
Business Acquisition [Line Items]
Gross carrying amount	$ 200
Weighted average useful life	9 months 18 days
Non-compete agreements
Business Acquisition [Line Items]
Gross carrying amount	$ 30
Weighted average useful life	1 year

Commitments and Contingencies - Legal Matters (Details) $ in Millions	3 Months Ended
	Sep. 30, 2018 USD ($)
Multiple existing lawsuits between Limelight Networks, Inc. (Limelight) and the Company \| Settled Litigation
Loss Contingencies [Line Items]
Settlement charge	$ 14.9

Debt - Narrative (Details) $ / shares in Units, shares in Millions	1 Months Ended		3 Months Ended	9 Months Ended
	Aug. 31, 2019 USD ($) d $ / shares shares	May 31, 2018 USD ($) d $ / shares shares	Sep. 30, 2019 USD ($) $ / shares	Sep. 30, 2019 USD ($) $ / shares	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Feb. 28, 2014 USD ($)
Debt Instrument [Line Items]
Repurchases of common stock			$ 175,500,000	$ 291,788,000	$ 625,925,000
Payments for note hedge transactions				312,225,000	261,740,000
Proceeds from sale of warrants				185,150,000	$ 119,945,000
Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 500,000,000.0
Debt term		5 years
Maximum borrowing capacity under specific conditions		$ 1,000,000,000.0
Outstanding borrowings			0	$ 0
Credit Agreement \| Minimum
Debt Instrument [Line Items]
Commitment fee				0.075%
Credit Agreement \| Minimum \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate				0.00%
Credit Agreement \| Minimum \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate				0.875%
Credit Agreement \| Maximum
Debt Instrument [Line Items]
Commitment fee				0.15%
Credit Agreement \| Maximum \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate				0.25%
Credit Agreement \| Maximum \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate				1.25%
2027 Notes \| Convertible Debt
Debt Instrument [Line Items]
Debt issued	$ 1,150,000,000.0		1,150,000,000	$ 1,150,000,000
Interest rate	0.375%
Threshold trading days exceeding price \| d	20
Threshold consecutive trading days exceeding price \| d	30
Threshold greater than percentage of stock price trigger	130.00%
Threshold trading days not exceeding price	5 years
Threshold consecutive trading days not exceeding price	5 years
Principal amount per conversion	$ 1,000
Threshold less than percentage of stock price trigger	98.00%
Conversion rate	0.0086073
Conversion price (in dollars per share) \| $ / shares	$ 116.18
Potential conversion shares of convertible debt (in shares) \| shares	9.9
Fair value of convertible senior notes			$ 1,172,800,000	$ 1,172,800,000
Closing price of common stock (in dollars per share) \| $ / shares			$ 91.38	$ 91.38
Repurchases of common stock	$ 100,000,000.0
Payments for purchase of convertible note hedge and warrant transactions	127,100,000
Payments for note hedge transactions	$ 312,200,000
Warrants outstanding (in shares) \| shares	9.9
Warrant strike price (in dollars per share) \| $ / shares	$ 178.74
Proceeds from sale of warrants	$ 185,200,000
Effective interest rate			3.10%	3.10%
2025 Notes \| Convertible Debt
Debt Instrument [Line Items]
Debt issued		$ 1,150,000,000.0	$ 1,150,000,000	$ 1,150,000,000		$ 1,150,000,000
Interest rate		0.125%
Threshold trading days exceeding price \| d		20
Threshold consecutive trading days exceeding price \| d		30
Threshold greater than percentage of stock price trigger		130.00%
Threshold trading days not exceeding price		5 days
Threshold consecutive trading days not exceeding price		5 days
Principal amount per conversion		$ 1,000
Threshold less than percentage of stock price trigger		98.00%
Conversion rate		0.010515
Conversion price (in dollars per share) \| $ / shares		$ 95.10
Potential conversion shares of convertible debt (in shares) \| shares		12.1
Fair value of convertible senior notes			$ 1,319,600,000	$ 1,319,600,000
Closing price of common stock (in dollars per share) \| $ / shares			$ 91.38	$ 91.38
Repurchases of common stock		$ 46,200,000
Payments for purchase of convertible note hedge and warrant transactions		141,800,000
Payments for note hedge transactions		$ 261,700,000
Warrants outstanding (in shares) \| shares		12.1
Warrant strike price (in dollars per share) \| $ / shares		$ 149.18
Proceeds from sale of warrants		$ 119,900,000
Effective interest rate			4.26%	4.26%
2019 Notes \| Convertible Debt
Debt Instrument [Line Items]
Debt issued							$ 690,000,000.0
Effective interest rate			3.20%	3.20%

Debt - Schedule of Convertible Senior Notes (Details) - Convertible Debt - USD ($)	Sep. 30, 2019	Aug. 31, 2019	Dec. 31, 2018	May 31, 2018
2027 Notes
Liability component:
Principal	$ 1,150,000,000	$ 1,150,000,000.0
Less: debt discount and issuance costs, net of amortization	(229,454,000)
Net carrying amount	920,546,000
Equity component:	220,529,000
2025 Notes
Liability component:
Principal	1,150,000,000		$ 1,150,000,000	$ 1,150,000,000.0
Less: debt discount and issuance costs, net of amortization	(247,098,000)		(275,920,000)
Net carrying amount	902,902,000		874,080,000
Equity component:	$ 285,225,000		$ 285,225,000

Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 12,982	$ 15,295	$ 35,657	$ 31,045
Capitalization of interest expense	(1,849)	(1,210)	(4,896)	(3,200)
Total interest expense	12,127	14,566	32,689	28,620
Credit Agreement
Debt Instrument [Line Items]
Interest on debt instruments	156	122	372	261
Convertible Debt \| 2025 Notes
Debt Instrument [Line Items]
Interest on debt instruments	359	359	1,077	514
Convertible Debt \| 2027 Notes
Debt Instrument [Line Items]
Interest on debt instruments	$ 479	$ 0	$ 479	$ 0

Leases (Details) $ in Thousands	3 Months Ended	9 Months Ended
Leases (Details) $ in Thousands	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 37,659	$ 113,588
Short-term lease cost	3,535	10,928
Variable lease cost	10,670	27,424
Sublease income	(839)	(2,791)
Total operating lease costs	51,025	149,149
Operating leases for real estate facilities that have not yet commenced	$ 553,000	$ 553,000
operating leases for real estate facilities that have not yet commenced term		15 years
Real Estate Arrangements
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term (in years)	10 years	10 years
Weighted average discount rate	4.10%	4.10%
Remainder of 2019	$ 10,975	$ 10,975
2020	49,206	49,206
2021	45,094	45,094
2022	41,090	41,090
2023	39,245	39,245
Thereafter	200,317	200,317
Total lease payments	385,927	385,927
Less: imputed interest	84,087	84,087
Total lease liabilities	301,840	301,840
Real Estate Arrangements \| General and administrative
Lessee, Lease, Description [Line Items]
Operating lease cost	14,517	43,506
Short-term lease cost	26	231
Variable lease cost	3,617	10,655
Sublease income	(839)	(2,791)
Total operating lease costs	$ 17,321	$ 51,601
Co-location Arrangements
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term (in years)	3 years 3 months 18 days	3 years 3 months 18 days
Weighted average discount rate	2.30%	2.30%
Remainder of 2019	$ 27,688	$ 27,688
2020	29,454	29,454
2021	9,789	9,789
2022	5,767	5,767
2023	3,944	3,944
Thereafter	10,158	10,158
Total lease payments	86,800	86,800
Less: imputed interest	4,931	4,931
Total lease liabilities	81,869	81,869
Co-location Arrangements \| Cost of revenues
Lessee, Lease, Description [Line Items]
Operating lease cost	23,142	70,082
Short-term lease cost	3,509	10,697
Variable lease cost	7,053	16,769
Sublease income	0	0
Total operating lease costs	$ 33,704	$ 97,548

Leases - Minimum Aggregate Future Obligations Under Non-cancelable Leases and Narrative (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Real Estate Arrangements
Lessee, Lease, Description [Line Items]
2019	$ 54,561
2020	78,683
2021	75,991
2022	72,579
2023	70,101
Thereafter	599,339
Total	951,254
Bandwidth and Co-location Arrangements
Lessee, Lease, Description [Line Items]
2019	138,777
2020	24,420
2021	8,463
2022	5,233
2023	2,156
Thereafter	3,709
Total	$ 182,758

Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended	24 Months Ended
Restructuring (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring charges incurred			$ 6,700		$ 19,000	$ 62,600
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			10,981
Costs incurred	$ (300)	$ (732)	6,879	$ 14,442
Cash disbursements			(17,200)
Balance as of September 30, 2019	660		660		660	660
Employee Severance and Related Benefits
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			10,508
Costs incurred			6,825
Cash disbursements			(16,839)
Balance as of September 30, 2019	494		494		494	494
Software Charges
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			198
Costs incurred			0
Cash disbursements			(99)
Balance as of September 30, 2019	99		99		99	99
Excess Facilities, Contract Terminations and Other
Restructuring Reserve [Roll Forward]
Balance as of January 1, 2019			275
Costs incurred			54
Cash disbursements			(262)
Balance as of September 30, 2019	$ 67		$ 67		$ 67	$ 67

Stockholders' Equity - Narrative (Details) - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Nov. 30, 2018
Class of Stock [Line Items]
Stock repurchase program, authorized amount					$ 1,100,000,000
Repurchases of common stock	$ (175,500,000)		$ (291,788,000)	$ (625,925,000)
Amortization expense from capitalized stock-based compensation	$ 7,500,000	$ 6,600,000	$ 22,900,000	$ 18,100,000
Common Stock
Class of Stock [Line Items]
Shares repurchased during period (in shares)	2.0		3.6

Stockholders' Equity - Schedule of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 46,815	$ 46,632	$ 140,262	$ 138,815
Provision for income taxes	(14,867)	(7,802)	(41,658)	(37,692)
Total stock-based compensation, net of income taxes	31,948	38,830	98,604	101,123
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	5,555	5,494	16,917	16,343
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	12,842	11,249	36,943	32,684
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	15,593	16,835	46,384	49,543
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 12,825	$ 13,054	$ 40,018	$ 40,245

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$ 3,394,764	$ 3,445,278	$ 3,191,860	$ 3,362,469
Other comprehensive (loss) income	(13,940)	(6,247)	(7,512)	(26,288)
Ending Balance	3,501,600	3,155,531	3,501,600	3,155,531
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(42,484)	(41,971)	(48,912)	(21,930)
Ending Balance	(56,424)	$ (48,218)	(56,424)	$ (48,218)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance			(51,904)
Other comprehensive (loss) income			(10,744)
Ending Balance	(62,648)		(62,648)
Net Unrealized Gains on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance			2,992
Other comprehensive (loss) income			3,232
Ending Balance	$ 6,224		$ 6,224

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) division	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) division	Sep. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Revenue	$ 709,912	$ 669,628	$ 2,121,494	$ 2,001,111
Number of divisions \| division	2		2
Web Division
Disaggregation of Revenue [Line Items]
Revenue	$ 390,223	357,255	$ 1,146,872	1,062,376
Media and Carrier Division
Disaggregation of Revenue [Line Items]
Revenue	319,689	312,373	974,622	938,735
U.S.
Disaggregation of Revenue [Line Items]
Revenue	413,116	412,573	1,248,175	1,249,041
International
Disaggregation of Revenue [Line Items]
Revenue	$ 296,796	$ 257,055	$ 873,319	$ 752,070

Revenue from Contracts with Customers - Performance Obligation (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue recognized	$ 51.0	$ 64.3
Remaining performance obligation	$ 2,300.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, percentage	70.00%
Remaining performance obligation, expected timing	1 year

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Estimated income tax charge		$ 15.0
Effective income tax rate		10.60%	11.20%
Increase in valuation allowance	$ 11.2

Net Income per Share - Schedule of Components Used in Diluted and Basic Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income (in dollars)	$ 137,890	$ 107,583	$ 358,935	$ 204,358
Denominator:
Shares used for basic net income per share (in shares)	162,445	165,924	163,029	168,763
Effect of dilutive securities:
Stock options (in shares)	36	80	59	158
RSUs and DSUs (in shares)	2,077	1,896	1,700	1,811
Convertible senior notes (in shares)	0	0	0	0
Warrants related to issuance of convertible senior notes (in shares)	0	0	0	0
Shares used for diluted net income per share (in shares)	164,558	167,900	164,788	170,732
Basic net income per share (in dollars per share)	$ 0.85	$ 0.65	$ 2.20	$ 1.21
Diluted net income per share (in dollars per share)	$ 0.84	$ 0.64	$ 2.18	$ 1.20

Net Income per Share - Schedule of Shares Excluded from Computation of Diluted EPS (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	45,605	41,294	46,425	42,182
Service-based RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	139	185	959	1,068
Performance-based RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	1,484	1,515	1,484	1,520
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	21,991	19,797	21,991	19,797
Warrants related to issuance of convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	21,991	19,797	21,991	19,797