Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 478,035	$ 298,373	$ 222,766
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	440,674	434,520	372,313
Stock-based compensation	187,140	183,813	164,308
Provision (benefit) for deferred income taxes	933	2,339	(7,244)
Amortization of debt discount and issuance costs	45,857	41,958	18,839
Restructuring-related software charge	3,784	4,940	31,965
Other non-cash reconciling items, net	4,744	12,078	10,068
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(64,471)	(30,445)	(50,054)
Prepaid expenses and other current assets	11,689	(4,132)	(28,968)
Accounts payable and accrued expenses	8,769	42,238	33,232
Deferred revenue	(13,547)	(919)	2,938
Other current liabilities	(17,230)	9,422	16,378
Other non-current assets and liabilities	(28,073)	14,142	14,442
Net cash provided by operating activities	1,058,304	1,008,327	800,983
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(165,329)	(79)	(369,073)
Cash paid for equity method investment	(36,008)	0	0
Purchases of property and equipment	(359,667)	(217,609)	(254,146)
Capitalization of internal-use software development costs	(202,410)	(188,132)	(160,632)
Purchases of short-and long-term marketable securities	(1,990,148)	(873,697)	(326,497)
Proceeds from sales of short-and long-term marketable securities	856	16,569	219,916
Proceeds from maturities of short-and long-term marketable securities	1,084,373	758,481	432,853
Other non-current assets and liabilities	399	(2,066)	(1,586)
Net cash used in investing activities	(1,667,934)	(506,533)	(459,165)
Cash flows from financing activities:
Proceeds from the issuance of convertible senior notes	1,135,629	1,132,185	0
Proceeds from the issuance of warrants	185,150	119,945	0
Purchase of note hedge related to convertible senior notes	(312,225)	(261,740)	0
Repayment of convertible senior notes	(690,000)	0	0
Proceeds related to the issuance of common stock under stock plans	57,112	62,608	55,680
Employee taxes paid related to net share settlement of stock-based awards	(75,266)	(64,305)	(58,395)
Repurchases of common stock	(334,519)	(750,000)	(361,194)
Other non-current assets and liabilities	(1,558)	(5,085)	(1,096)
Net cash (used in) provided by financing activities	(35,677)	233,608	(365,005)
Effects of exchange rate changes on cash and cash equivalents	2,466	(12,844)	12,990
Net (decrease) increase in cash and cash equivalents	(642,841)	722,558	(10,197)
Cash, cash equivalents and restricted cash at beginning of year	1,036,987	314,429	324,626
Cash, cash equivalents and restricted cash at end of year	394,146	1,036,987	314,429
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds received in the years ended December 31, 2019, 2018 and 2017 of $3,731, $18,501 and $6,750, respectively	73,898	45,129	91,640
Cash paid for interest expense	1,438	639	0
Cash paid for operating lease liabilities	153,818
Non-cash activities:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	529,376
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	88,238	54,867	27,209
Capitalization of stock-based compensation	$ 35,905	$ 34,785	$ 28,851