Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 285,061	$ 221,045
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	231,788	214,270
Stock-based compensation	96,684	93,447
Provision for deferred income taxes	11,394	24,608
Amortization of debt discount and issuance costs	31,310	19,628
Other non-cash reconciling items, net	14,804	1,180
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(105,546)	(38,127)
Prepaid expenses and other current assets	(9,979)	(23,287)
Accounts payable and accrued expenses	(47,402)	(52,789)
Deferred revenue	21,342	27,973
Other current liabilities	(1,115)	(18,739)
Other non-current assets and liabilities	(6,407)	9,570
Net cash provided by operating activities	521,934	478,779
Cash flows from investing activities:
Cash received (paid) for business acquisitions, net of cash acquired	106	(121,409)
Cash paid for asset acquisition	(36,376)	0
Cash paid for equity method investment	0	(36,008)
Purchases of property and equipment	(214,952)	(158,158)
Capitalization of internal-use software development costs	(120,716)	(117,620)
Purchases of short- and long-term marketable securities	(842,516)	(391,758)
Proceeds from sales of short- and long-term marketable securities	29,667	268
Proceeds from maturities of short- and long-term marketable securities	984,333	649,262
Other non-current assets and liabilities	79	2,237
Net cash used in investing activities	(200,375)	(173,186)
Cash flows from financing activities:
Repayment of convertible senior notes	0	(690,000)
Proceeds related to the issuance of common stock under stock plans	29,805	28,772
Employee taxes paid related to net share settlement of stock-based awards	(63,930)	(49,956)
Repurchases of common stock	(107,880)	(116,247)
Other non-current assets and liabilities	0	(1,558)
Net cash used in financing activities	(142,005)	(828,989)
Effects of exchange rate changes on cash, cash equivalents and restricted cash	(828)	2,678
Net increase (decrease) in cash, cash equivalents and restricted cash	178,726	(520,718)
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	572,872	516,269
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds received of $6,711 and $2,216 for the six months ended June 30, 2020 and 2019, respectively	26,409	54,271
Cash paid for interest expense	3,079	719
Cash paid for operating lease liabilities	94,157	69,317
Non-cash activities:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	65,832	63,709
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	98,235	71,066
Capitalization of stock-based compensation	$ 18,856	$ 18,760