UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net income (loss)	$ 30,674	$ (46,112)
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities
Stock-based compensation	60,788	48,831
(Gain) on capped call transactions	(7,192)	(827)
Deferred income taxes	(28,232)	(18,399)
Amortization of deferred commissions	21,202	16,061
Amortization of debt discount and issuance costs	1,348	6,033
Amortization of intangible assets and depreciation	15,504	10,134
Amortization of investments	1,988	0
Foreign currency transaction loss	5,501	1,691
Other non-cash	(4,869)	6,445
Change in operating assets and liabilities, net	(77,302)	(45,056)
Cash provided by (used in) operating activities	19,410	(21,199)
Investing activities
Purchases of investments	(51,601)	(1,769)
Proceeds from maturities and called investments	68,798	0
Sales of investments	2,450	1,424
Payments for acquisitions, net of cash acquired	(4,993)	0
Investment in property and equipment	(4,161)	(19,059)
Cash provided by (used in) investing activities	10,493	(19,404)
Financing activities
Proceeds from issuance of convertible senior notes	0	600,000
Purchase of capped calls related to convertible senior notes	0	(51,900)
Payment of debt issuance costs	0	(14,527)
Proceeds from employee stock purchase plan	5,146	1,403
Dividend payments to stockholders	(4,865)	(4,793)
Common stock repurchases	(60,998)	(44,890)
Cash (used in) provided by financing activities	(60,717)	485,293
Effect of exchange rate changes on cash and cash equivalents	(1,207)	(942)
Net (decrease) increase in cash and cash equivalents	(32,021)	443,748
Cash and cash equivalents, beginning of period	171,899	68,363
Cash and cash equivalents, end of period	$ 139,878	$ 512,111