CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net loss	$ (58,884)	$ (47,174)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	21,478	24,502
Non-cash leases expense	6,593	6,830
Stock-based compensation expense, net of amounts capitalized	49,172	36,973
Deferred income taxes	197	195
Bad debt expense	590	790
Gain on sale of a private company investment	0	(1,001)
Other	310	888
Changes in assets and liabilities:
Accounts receivable	840	(1,506)
Prepaid expenses and other assets	(7,530)	(6,714)
Accounts payable and accrued liabilities	12,691	5,659
Accrued compensation	(1,052)	(4,408)
Deferred revenue	26,678	18,720
Operating lease liabilities	(7,522)	(7,659)
Net cash provided by operating activities	43,561	26,095
Cash flows from investing activities
Purchases of property and equipment	(322)	(772)
Capitalized internal-use software	(4,418)	(5,372)
Proceeds from sale of a private company investment	0	1,001
Net cash used in investing activities	(4,740)	(5,143)
Cash flows from financing activities
Proceeds from stock option exercises	17,703	24,279
Proceeds from employee stock purchase plan	3,873	3,082
Repayment of debt	(1,100)	(1,100)
Net cash provided by financing activities	20,476	26,261
Effect of exchange rate changes on cash	101	(1,090)
Net increase in cash, cash equivalents and restricted cash	59,398	46,123
Cash, cash equivalents and restricted cash at beginning of period	224,614	131,683
Cash, cash equivalents and restricted cash at end of period	284,012	177,806
Supplemental cash flow data:
Interest paid for term debt	4,267	5,198
Income taxes paid	618	394
Non-cash investing and financing transactions:
Stock compensation included in capitalized software costs	1,136	1,486
Lease liabilities arising from obtaining right-of-use assets, net	2,676	0
Proceeds receivable from stock option exercises	$ 77	$ 1,350