Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Cash flows from operating activities:
Net loss		$ (26,704)	$ (116,846)	[1],[2]	$ (414,249)	[1],[2]
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization		149,604	113,875	[2]	83,082	[2]
Amortization of deferred commissions		143,358	99,105	[2]	69,565	[2]
Amortization of debt discount and issuance costs		52,733	53,394	[2]	33,278	[2]
Stock-based compensation		543,953	394,004	[2]	317,654	[2]
Deferred income tax		(34,180)	(5,724)	[2]	(658)	[2]
Gain on marketable equity securities		(19,257)	0	[2]	0	[2]
Repayments of convertible senior notes attributable to debt discount		(145,349)	0	[2]	0	[2]
Other		6,177	(905)	[2]	3,764	[2]
Changes in operating assets and liabilities, net of effect of business combinations:
Accounts receivable		(146,148)	(99,693)	[2]	(126,415)	[2]
Deferred commissions		(239,382)	(190,246)	[2]	(151,921)	[2]
Prepaid expenses and other assets		(19,886)	(34,288)	[2]	(24,164)	[2]
Accounts payable		(4,757)	(5,504)	[2]	(3,554)	[2]
Deferred revenue		468,856	369,242	[2]	285,139	[2]
Accrued expenses and other liabilities		82,071	66,526	[2]	87,560	[2]
Net cash provided by operating activities		811,089	642,940	[2]	159,081	[2]
Cash flows from investing activities:
Purchases of property and equipment		(224,462)	(150,510)	[2]	(105,562)	[2]
Business combinations, net of cash and restricted cash acquired		(37,440)	(58,203)	[2]	(34,297)	[2]
Purchases of other intangibles		(24,400)	(6,670)	[2]	(18,750)	[2]
Purchases of investments		(1,285,943)	(1,189,511)	[2]	(518,664)	[2]
Purchases of strategic investments		(9,839)	(4,750)	[2]	(500)	[2]
Sales of investments		39,975	85,106	[2]	297,998	[2]
Maturities of investments		1,194,687	440,590	[2]	271,537	[2]
Net cash used in investing activities		(347,422)	(883,948)	[2]	(108,238)	[2]
Cash flows from financing activities:
Net proceeds from borrowings on convertible senior notes		0	772,127	[2]	0	[2]
Repayments of convertible senior notes attributable to principal		(429,645)	(4)	[2]	0	[2]
Proceeds from issuance of warrants		0	54,071	[2]	0	[2]
Purchases of convertible note hedges		0	(128,017)	[2]	0	[2]
Repurchases and retirement of common stock		0	(55,000)	[2]	0	[2]
Proceeds from employee stock plans		104,160	82,567	[2]	66,378	[2]
Taxes paid related to net share settlement of equity awards		(281,010)	(181,938)	[2]	(119,907)	[2]
Payments on financing obligations		(933)	(4,914)	[2]	(2,223)	[2]
Net cash (used in) provided by financing activities		(607,428)	538,892	[2]	(55,752)	[2]
Foreign currency effect on cash, cash equivalents and restricted cash		(15,530)	28,013	[2]	(5,945)	[2]
Net (decrease) increase in cash, cash equivalents and restricted cash		(159,291)	325,897	[2]	(10,854)	[2]
Cash, cash equivalents and restricted cash at beginning of period	[2]	727,829	401,932		412,786
Cash, cash equivalents and restricted cash at end of period		568,538	727,829	[2]	401,932	[2]
Cash, cash equivalents and restricted cash at end of period:
Total cash, cash equivalents and restricted cash shown in the consolidated statement of cash flows		568,538	401,932	[2]	401,932	[2]
Supplemental disclosures of other cash flow information:
Income taxes paid, net of refunds		17,507	7,899	[2]	4,338	[2]
Non-cash investing and financing activities:
Settlement of 2018 Notes conversion feature		773,302	0	[2]	0	[2]
Benefit from exercise of 2018 Note Hedge		766,858	0	[2]	0	[2]
Property and equipment included in accounts payable and accrued expenses		25,767	15,007	[2]	15,381	[2]
Purchases of intangible assets included in accrued expenses and other liabilities		$ 8,500	$ 6,750	[2]	$ 6,210	[2]

[1] As adjusted to reflect the impact of the full retrospective adoption of Topic 606.

[2] As adjusted to reflect the impact of the full retrospective adoption of Topic 606.