CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (99,013)	$ (73,521)	$ (41,022)
Adjustments to reconcile net loss to net cash used in operating activities:
Deferred income taxes	4,243	0	(873)
Depreciation and amortization	6,880	6,192	4,692
Stock-based compensation	41,610	22,875	7,760
Other	(784)	533	125
Changes in operating assets and liabilities:
Accounts receivable	(25,941)	(17,408)	(14,769)
Prepaid expenses and other current assets	(5,188)	(6,105)	(8,345)
Deferred commissions	(12,831)	(9,258)	(20,058)
Other assets	(3,336)	(1,876)	(3,267)
Accounts payable and accrued expenses	4,244	294	1,922
Accrued compensation	6,269	11,112	4,298
Deferred revenue	72,799	64,085	63,404
Other current liabilities	255	408	421
Other liabilities	49	110	(554)
Net cash used in operating activities	(10,744)	(2,559)	(6,266)
Cash flows from investing activities:
Purchases of property and equipment	(20,674)	(5,733)	(2,755)
Purchases of investments	(242,059)	(117,488)	0
Sales and maturities of investments	224,594	0	0
Business combination, net of cash acquired	(74,911)	0	0
Net cash used in investing activities	(113,050)	(123,221)	(2,755)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting discounts and commissions	0	268,531	0
Payments of costs related to initial public offering	0	(3,932)	0
Principal payments under finance lease obligations	(16)	(1,443)	(306)
Credit facility issuance costs	0	0	(238)
Proceeds from stock issued in connection with the employee stock purchase plan	15,129	0	0
Proceeds from the exercise of stock options	19,048	1,668	3,020
Repurchases of common stock	0	(75)	(385)
Net cash provided by financing activities	34,161	264,749	2,091
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(1,080)	(1,063)	(68)
Net (decrease) increase in cash and cash equivalents and restricted cash	(90,713)	137,906	(6,998)
Cash and cash equivalents and restricted cash at beginning of year	165,378	27,472	34,470
Cash and cash equivalents and restricted cash at end of year	74,665	165,378	27,472
Supplemental disclosure of cash flow information:
Cash paid for interest	96	111	79
Cash paid for income taxes	$ 8,530	$ 1,207	$ 642