CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (91,581)	$ (73,859)	$ (154,740)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	47,822	45,133	48,068
Non-cash leases expense	13,092	12,537	0
Stock-based compensation expense, net of amounts capitalized	79,167	60,245	131,770
Deferred income taxes	814	(3,676)	(508)
Bad debt expense	1,352	432	186
Loss on debt extinguishment	0	0	941
Gain on sale of a private company investment	(1,001)	(1,001)	(999)
Impairment of property and equipment	0	0	2,821
Other	1,588	(157)	1,798
Changes in assets and liabilities:
Accounts receivable	(7,643)	(7,671)	(2,144)
Prepaid expenses and other assets	(12,106)	(5,172)	(5,565)
Accounts payable and accrued liabilities	1,148	8,318	3,564
Accrued interest on financing lease obligation, net of payments	0	0	(1,376)
Accrued compensation	7,865	2,232	5,203
Deferred revenue	29,742	31,181	16,353
Operating lease liabilities	(14,629)	(13,890)	0
Net cash provided by operating activities	55,630	54,652	45,372
Cash flows from investing activities
Acquisitions, net of cash acquired	0	(114,603)	0
Purchases of property and equipment	(782)	(2,450)	(9,981)
Capitalized internal-use software	(9,220)	(12,034)	(12,052)
Proceeds from sale of a private company investment and other	1,095	1,001	999
Net cash used in investing activities	(8,907)	(128,086)	(21,034)
Cash flows from financing activities
Proceeds from initial public offering, net	0	0	232,509
Payments of deferred offering costs	0	0	(7,173)
Proceeds from stock option exercises	42,150	47,678	494
Proceeds from employee stock purchase plan	6,719	5,344	0
Employee payroll taxes paid for net share settlement of restricted stock units	0	0	(25,807)
Payments to repurchase common stock	0	0	(16)
Repayment of debt	(2,200)	(2,200)	(104,050)
Payment of debt issuance costs and other	0	0	(482)
Net cash provided by financing activities	46,669	50,822	95,475
Effect of exchange rate changes on cash	(461)	(76)	(787)
Net increase (decrease) in cash, cash equivalents and restricted cash	92,931	(22,688)	119,026
Cash, cash equivalents and restricted cash at beginning of period	131,683	154,371	35,345
Cash, cash equivalents and restricted cash at end of period	224,614	131,683	154,371
Supplemental cash flow data:
Interest paid for term debt	9,590	13,502	20,466
Income taxes paid	583	756	535
Non-cash investing and financing transactions:
Fair value of common stock issued as acquisitions consideration	0	36,204	0
Stock compensation included in capitalized software costs	2,243	3,503	2,609
Lease liabilities arising from obtaining right-of-use assets, net	0	7,937	0
Derecognized financing obligation related to building due to adoption of ASC 842	0	92,009	0
Derecognized building due to adoption of ASC 842	$ 0	$ 71,781	$ 0