CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 312,192	$ 285,061
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	269,186	231,788
Stock-based compensation	104,786	96,684
Provision for deferred income taxes	7,225	11,394
Amortization of debt discount and issuance costs	32,717	31,310
Other non-cash reconciling items, net	13,654	14,804
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(4,404)	(105,546)
Prepaid expenses and other current assets	(10,849)	(9,979)
Accounts payable and accrued expenses	(83,059)	(47,402)
Deferred revenue	18,094	21,342
Other current liabilities	(16,230)	(1,115)
Other non-current assets and liabilities	(15,386)	(6,407)
Net cash provided by operating activities	627,926	521,934
Cash flows from investing activities:
Cash (paid) received for business acquisitions, net of cash acquired	(15,638)	106
Cash paid for asset acquisition	0	(36,376)
Purchases of property and equipment	(194,453)	(214,952)
Capitalization of internal-use software development costs	(124,835)	(120,716)
Purchases of short- and long-term marketable securities	(382,236)	(842,516)
Proceeds from sales of short- and long-term marketable securities	7,596	29,667
Proceeds from maturities of short- and long-term marketable securities	513,850	984,333
Other non-current assets and liabilities	(212)	79
Net cash used in investing activities	(195,928)	(200,375)
Cash flows from financing activities:
Proceeds related to the issuance of common stock under stock plans	31,122	29,805
Employee taxes paid related to net share settlement of stock-based awards	(76,260)	(63,930)
Repurchases of common stock	(154,416)	(107,880)
Other non-current assets and liabilities	(67)	0
Net cash used in financing activities	(199,621)	(142,005)
Effects of exchange rate changes on cash, cash equivalents and restricted cash	(4,148)	(828)
Net increase in cash, cash equivalents and restricted cash	228,229	178,726
Cash, cash equivalents and restricted cash at beginning of period	353,466	394,146
Cash, cash equivalents and restricted cash at end of period	581,695	572,872
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds received of $6,550 and $6,711 for the six months ended June 30, 2021 and 2020, respectively	56,995	26,409
Cash paid for interest expense	2,875	3,079
Cash paid for operating lease liabilities	117,632	94,157
Non-cash activities:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	131,962	65,832
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	43,520	98,235
Capitalization of stock-based compensation	19,524	18,856
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	581,068	572,288
Restricted cash	627	584
Cash, cash equivalents and restricted cash	$ 581,695	$ 572,872