Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 123,146	$ 107,130
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	116,208	108,205
Stock-based compensation	47,493	45,305
(Benefit) provision for deferred income taxes	(2,888)	8,982
Amortization of debt discount and issuance costs	15,633	11,618
Other non-cash reconciling items, net	12,052	(121)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(73,913)	(43,766)
Prepaid expenses and other current assets	(10,434)	(13,029)
Accounts payable and accrued expenses	(27,458)	(85,366)
Deferred revenue	26,989	29,286
Other current liabilities	928	(9,473)
Other non-current assets and liabilities	(4,513)	2,079
Net cash provided by operating activities	223,243	160,850
Cash flows from investing activities:
Cash received (paid) for business acquisitions, net of cash acquired	106	(121,464)
Cash paid for asset acquisition	(36,376)	0
Cash paid for equity method investment	0	(40,213)
Purchases of property and equipment	(141,095)	(69,752)
Capitalization of internal-use software development costs	(74,334)	(72,677)
Purchases of short- and long-term marketable securities	(389,779)	(10,625)
Proceeds from sales of short- and long-term marketable securities	1,179	244
Proceeds from maturities of short- and long-term marketable securities	529,637	547,793
Other non-current assets and liabilities	(76)	2,935
Net cash (used in) provided by investing activities	(110,738)	236,241
Cash flows from financing activities:
Repayment of convertible senior notes	0	(690,000)
Proceeds related to the issuance of common stock under stock plans	19,546	19,774
Employee taxes paid related to net share settlement of stock-based awards	(50,835)	(38,639)
Repurchases of common stock	(80,550)	(34,872)
Other non-current assets and liabilities	0	(1,558)
Net cash used in financing activities	(111,839)	(745,295)
Effects of exchange rate changes on cash, cash equivalents and restricted cash	(8,983)	1,601
Net decrease in cash, cash equivalents and restricted cash	(8,317)	(346,603)
Cash, cash equivalents and restricted cash at beginning of period	394,146	1,036,987
Cash, cash equivalents and restricted cash at end of period	385,829	690,384
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds received of $1,204 and $1,176 for the three months ended March 31, 2020 and 2019, respectively	21,440	44,165
Cash paid for interest expense	2,360	0
Cash paid for operating lease liabilities	47,066	30,504
Non-cash activities:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	31,050	29,257
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	22,874	49,627
Capitalization of stock-based compensation	$ 8,722	$ 8,831