Nature of Business and Basis of Presentation (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment country server $ / shares	Mar. 31, 2017 USD ($) $ / shares	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of servers (more than) | server	200,000
Number of countries in which servers are located | country	130
Number of industry segments | segment	1
Current assets:
Accounts receivable	$ 484,617		$ 461,457
Prepaid expenses and other current assets	163,556		172,853
Total current assets	1,459,726		1,346,246
Deferred income tax assets	44,490		36,231
Other assets	133,166		136,365
Total assets	4,686,904		4,648,916
Current liabilities:
Deferred revenue	95,490		70,495
Total current liabilities	1,130,595		456,694
Deferred revenue	7,049		6,062
Deferred income tax liabilities	17,675		17,823
Total liabilities	1,300,647		1,286,447
Stockholders’ equity:
Accumulated deficit	(675,550)		(690,662)
Total stockholders’ equity	3,386,257		3,362,469
Total liabilities and stockholders’ equity	4,686,904		4,648,916
Revenue	668,724	$ 600,293
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)	234,825	205,727
Sales and marketing	122,553	114,492
Total costs and operating expenses	600,167	494,959
Income from operations	68,557	105,334
Income before provision for income taxes	67,693	104,677
Provision for income taxes	$ 13,979	$ 30,094
Net income per share:
Basic (in dollars per share) | $ / shares	$ 0.32	$ 0.43
Diluted (in dollars per share) | $ / shares	$ 0.31	$ 0.43
Comprehensive income	$ 57,310	$ 85,320
Cash flows from operating activities:
Net income	53,714	74,583
Adjustments to reconcile net income to net cash provided by operating activities:
(Benefit) provision for deferred income taxes	(7,814)	28,425
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(18,419)	(19,876)
Prepaid expenses and other current assets	(4,927)	(47,172)
Deferred revenue	25,243	10,043
Other non-current assets and liabilities	996	(12,948)
Net cash provided by operating activities	192,010	142,618
Cash flows from investing activities:
Other non-current assets and liabilities	(715)	(335)
Net cash (used in) provided by investing activities	(111,485)	140,306
Effects of exchange rate changes on cash, cash equivalents and restricted cash	1,165	5,019
Net increase in cash, and cash equivalents and restricted cash	51,029	199,085
Cash, cash equivalents and restricted cash at beginning of period	314,429	324,626
Cash, cash equivalents and restricted cash at end of period	$ 365,458	523,711
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		609,237
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)		205,703
Sales and marketing		113,566
Total costs and operating expenses		494,009
Income from operations		115,228
Income before provision for income taxes		114,571
Provision for income taxes		$ 33,641
Net income per share:
Basic (in dollars per share) | $ / shares		$ 0.47
Diluted (in dollars per share) | $ / shares		$ 0.46
Cash flows from operating activities:
Net income		$ 80,930
Adjustments to reconcile net income to net cash provided by operating activities:
(Benefit) provision for deferred income taxes		31,972
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable		(30,146)
Prepaid expenses and other current assets		(47,065)
Deferred revenue		10,876
Other non-current assets and liabilities		(13,512)
Net cash provided by operating activities		142,618
Cash flows from investing activities:
Other non-current assets and liabilities		(1,230)
Net cash (used in) provided by investing activities		139,411
Effects of exchange rate changes on cash, cash equivalents and restricted cash		4,979
Net increase in cash, and cash equivalents and restricted cash		198,150
Cash, cash equivalents and restricted cash at beginning of period		324,169
Cash, cash equivalents and restricted cash at end of period		522,319
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		(8,944)
Costs and operating expenses:
Cost of revenue (exclusive of amortization of acquired intangible assets shown below)		24
Sales and marketing		926
Total costs and operating expenses		950
Income from operations		(9,894)
Income before provision for income taxes		(9,894)
Provision for income taxes		$ (3,547)
Net income per share:
Basic (in dollars per share) | $ / shares		$ (0.04)
Diluted (in dollars per share) | $ / shares		$ (0.04)
Comprehensive income		$ 6,300
Cash flows from operating activities:
Net income		(6,347)
Adjustments to reconcile net income to net cash provided by operating activities:
(Benefit) provision for deferred income taxes		(3,547)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable		10,270
Prepaid expenses and other current assets		(107)
Deferred revenue		(833)
Other non-current assets and liabilities		564
Net cash provided by operating activities		0
Cash flows from investing activities:
Other non-current assets and liabilities		0
Net cash (used in) provided by 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
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:
(Benefit) 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		895
Net cash (used in) provided by investing activities		895
Effects of exchange rate changes on cash, cash equivalents and restricted cash		40
Net increase in cash, and cash equivalents and restricted cash		935
Cash, cash equivalents and restricted cash at beginning of period		457
Cash, cash equivalents and restricted cash at end of period		$ 1,392