CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net (loss)	$ (63,040)	$ (61,373)	$ (90,433)
Adjustments to reconcile net (loss) to cash provided by (used in) operating activities
Stock-based compensation	115,947	103,068	80,909
Deferred income taxes	(75,336)	(59,777)	(49,317)
Loss (gain) on capped call transactions	23,633	(31,697)	0
Amortization of deferred commissions	41,387	33,302	29,152
Lease expense	13,277	16,248	14,497
Amortization of debt discount and issuance costs	2,977	14,813	0
Amortization of intangible assets and depreciation	28,593	21,348	21,396
Amortization of investments	3,721	1,073	800
Foreign currency transaction loss (gain)	6,459	(3,704)	2,335
Other	1,032	(879)	(521)
Change in operating assets and liabilities:
Accounts receivable, unbilled receivables, and contract assets	(11,957)	(32,321)	1,088
Other current assets	17,209	(12,959)	(6,344)
Other current liabilities	(18,726)	37,945	25,670
Deferred revenue	41,279	43,661	1,937
Deferred commissions	(71,451)	(55,175)	(49,746)
Other long-term assets and liabilities	(15,886)	(14,136)	(23,588)
Cash provided by (used in) operating activities	39,118	(563)	(42,165)
Investing activities
Purchases of investments	(79,121)	(326,549)	(11,424)
Proceeds from maturities and called investments	105,977	28,811	13,634
Sales of investments	61,096	1,424	89,406
Payments for acquisitions, net of cash acquired	(4,993)	0	(10,934)
Investment in property and equipment	(10,456)	(25,369)	(10,608)
Cash provided by (used in) investing activities	72,503	(321,683)	70,074
Financing activities
Proceeds from issuance of convertible senior notes	0	600,000	0
Purchase of capped calls related to convertible senior notes	0	(51,900)	0
Payment of debt issuance costs	0	(14,527)	0
Proceeds from employee stock purchase plan	10,554	3,039	2,202
Dividend payments to stockholders	(9,761)	(9,628)	(9,486)
Proceeds from revolving credit facility	0	0	45,000
Payments on revolving credit facility	0	0	(45,000)
Common stock repurchases for tax withholdings for net settlement of equity awards	(69,925)	(75,562)	(44,839)
Common stock repurchases under stock repurchase program	(52,711)	(27,974)	(22,135)
Cash (used in) provided by financing activities	(121,843)	423,448	(74,258)
Effect of exchange rate changes on cash and cash equivalents	(1,712)	2,334	290
Net (decrease) increase in cash and cash equivalents	(11,934)	103,536	(46,059)
Cash and cash equivalents, beginning of period	171,899	68,363	114,422
Cash and cash equivalents, end of period	159,965	171,899	68,363
Supplemental disclosures
Interest paid on convertible notes	4,500	2,338	0
Income taxes (refunded) paid	(4,552)	3,377	4,745
Non-cash investing and financing activity:
Dividends payable	$ 2,454	$ 2,428	$ 2,388