Nature of Business and Basis of Presentation (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) country server $ / shares	Sep. 30, 2017 USD ($) $ / shares	Sep. 30, 2018 USD ($) segment country server $ / shares	Sep. 30, 2017 USD ($) $ / shares	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of servers (more than) | server	200,000		200,000
Number of countries in which servers are located (more than) | country	130		130
Number of industry segments | segment			1
Current assets:
Accounts receivable	$ 466,364		$ 466,364		$ 461,457
Prepaid expenses and other current assets	161,785		161,785		172,853
Total current assets	2,429,789		2,429,789		1,346,246
Deferred income tax assets	23,688		23,688		36,231
Other assets	103,284		103,284		136,365
Total assets	5,363,887		5,363,887		4,648,916
Current liabilities:
Deferred revenue	93,732		93,732		70,495
Total current liabilities	1,195,938		1,195,938		456,694
Deferred revenue	5,218		5,218		6,062
Deferred income tax liabilities	18,827		18,827		17,823
Total liabilities	2,208,357		2,208,357		1,286,447
Stockholders’ equity:
Accumulated deficit	(524,906)		(524,906)		(690,662)
Total stockholders’ equity	3,155,530		3,155,530		3,362,469
Total liabilities and stockholders’ equity	5,363,887		5,363,887		4,648,916
Revenue	669,628	$ 624,440	2,001,111	$ 1,830,565
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)	239,246	225,490	709,558	645,897
Sales and marketing	125,323	117,863	379,556	350,299
Total costs and operating expenses	553,091	533,187	1,758,900	1,548,385
Income from operations	116,537	91,253	242,211	282,180
Income before provision for income taxes	110,770	91,505	230,016	281,973
Provision for income taxes	$ 3,187	$ 27,594	$ 25,658	$ 86,727
Net income per share:
Basic (in dollars per share) | $ / shares	$ 0.65	$ 0.37	$ 1.21	$ 1.13
Diluted (in dollars per share) | $ / shares	$ 0.64	$ 0.37	$ 1.20	$ 1.13
Comprehensive income	$ 101,336	$ 71,910	$ 178,070	$ 227,868
Cash flows from operating activities:
Net income	107,583	63,911	204,358	195,246
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes			12,906	23,134
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable			(13,611)	(9,423)
Prepaid expenses and other current assets			(2,084)	(36,580)
Deferred revenue			23,927	1,528
Other non-current assets and liabilities			(10,338)	(8,828)
Net cash provided by operating activities			722,172	603,542
Cash flows from investing activities:
Other non-current assets and liabilities			(2,678)	(1,166)
Net cash used in investing activities			(678,234)	(257,012)
Effects of exchange rate changes on cash, cash equivalents and restricted cash			(11,528)	12,359
Net increase in cash, and cash equivalents and restricted cash			392,142	44,782
Cash, cash equivalents and restricted cash at beginning of period			314,429	324,626
Cash, cash equivalents and restricted cash at end of period	$ 706,571	369,408	$ 706,571	369,408
Prepaid and other current assets | Intra-Entity Asset Transfers
Cash flows from investing activities:
Cumulative-effect adjustment					11,600
Deferred costs included in other assets | Intra-Entity Asset Transfers
Cash flows from investing activities:
Cumulative-effect adjustment					27,000
As Previously Reported
Current assets:
Accounts receivable					459,127
Prepaid expenses and other current assets					137,809
Total current assets					1,308,872
Deferred income tax assets					51,069
Other assets					112,829
Total assets					4,602,844
Current liabilities:
Deferred revenue					77,705
Total current liabilities					463,904
Deferred revenue					6,839
Deferred income tax liabilities					15,510
Total liabilities					1,292,121
Stockholders’ equity:
Accumulated deficit					(742,408)
Total stockholders’ equity					3,310,723
Total liabilities and stockholders’ equity					4,602,844
Revenue		621,399		1,839,544
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)		225,468		645,821
Sales and marketing		120,220		353,218
Total costs and operating expenses		535,522		1,551,228
Income from operations		85,877		288,316
Income before provision for income taxes		86,129		288,109
Provision for income taxes		$ 25,617		$ 88,895
Net income per share:
Basic (in dollars per share) | $ / shares		$ 0.35		$ 1.16
Diluted (in dollars per share) | $ / shares		$ 0.35		$ 1.15
Cash flows from operating activities:
Net income		$ 60,512		$ 199,214
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes				25,302
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable				(19,199)
Prepaid expenses and other current assets				(34,195)
Deferred revenue				991
Other non-current assets and liabilities				(7,036)
Net cash provided by operating activities				603,542
Cash flows from investing activities:
Other non-current assets and liabilities				(1,895)
Net cash used in investing activities				(257,741)
Effects of exchange rate changes on cash, cash equivalents and restricted cash				12,289
Net increase in cash, and cash equivalents and restricted cash				43,983
Cash, cash equivalents and restricted cash at beginning of period				324,169
Cash, cash equivalents and restricted cash at end of period		368,152		368,152
Adjustments | Accounting Standards Update 2014-09
Current assets:
Accounts receivable					2,330
Prepaid expenses and other current assets					35,044
Total current assets					37,374
Deferred income tax assets					(14,838)
Other assets					23,536
Total assets					46,072
Current liabilities:
Deferred revenue					(7,210)
Total current liabilities					(7,210)
Deferred revenue					(777)
Deferred income tax liabilities					2,313
Total liabilities					(5,674)
Stockholders’ equity:
Accumulated deficit					51,746
Total stockholders’ equity					51,746
Total liabilities and stockholders’ equity					$ 46,072
Revenue		3,041		(8,979)
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)		22		76
Sales and marketing		(2,357)		(2,919)
Total costs and operating expenses		(2,335)		(2,843)
Income from operations		5,376		(6,136)
Income before provision for income taxes		5,376		(6,136)
Provision for income taxes		$ 1,977		$ (2,168)
Net income per share:
Basic (in dollars per share) | $ / shares		$ 0.02		$ (0.03)
Diluted (in dollars per share) | $ / shares		$ 0.02		$ (0.02)
Comprehensive income		$ 3,400		$ (4,000)
Cash flows from operating activities:
Net income		3,399		(3,968)
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes				(2,168)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable				9,776
Prepaid expenses and other current assets				(2,385)
Deferred revenue				537
Other non-current assets and liabilities				(1,792)
Net cash provided by operating activities				0
Cash flows from investing activities:
Other non-current assets and liabilities				0
Net cash used in investing activities				0
Effects of exchange rate changes on cash, cash equivalents and restricted cash				0
Net increase in cash, and cash equivalents and restricted cash				0
Cash, cash equivalents and restricted cash at beginning of period				0
Cash, cash equivalents and restricted cash at end of period		0		0
Adjustments | Accounting Standards Update 2016-18
Cash flows from operating activities:
Net income				0
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes				0
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable				0
Prepaid expenses and other current assets				0
Deferred revenue				0
Other non-current assets and liabilities				0
Net cash provided by operating activities				0
Cash flows from investing activities:
Other non-current assets and liabilities				729
Net cash used in investing activities				729
Effects of exchange rate changes on cash, cash equivalents and restricted cash				70
Net increase in cash, and cash equivalents and restricted cash				799
Cash, cash equivalents and restricted cash at beginning of period				457
Cash, cash equivalents and restricted cash at end of period		$ 1,256		$ 1,256