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	$ (50,714)	$ (49,451)	$ (31,007)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	4,742	2,021	886
Loss (gain) on disposal of equipment	146	(4)	0
Bad debt expense	99	211	62
Deferred income taxes	(334)	(218)	(251)
Stock-based compensation	16,443	16,054	12,976
Fair value adjustment for warrant liability	0	0	341
Loss on extinguishment of debt	0	0	384
Changes in assets and liabilities:
Accounts receivable	7,432	(23,332)	(9,716)
Prepaid expenses and other assets	8,972	(1,025)	(4,162)
Deferred commissions	(9,319)	(7,615)	(3,487)
Accounts payable and accrued expenses	(4,039)	7,461	4,128
Accrued compensation and related benefits	(3,072)	(3)	2,365
Other current liabilities	1,318	1,823	383
Deferred revenue	12,573	23,023	18,344
Operating lease liabilities	6,827
Deferred rent, non-current	0	(266)	(374)
Net cash used in operating activities	(8,926)	(31,321)	(9,128)
Cash flows from investing activities:
Purchases of property and equipment	(32,421)	(7,014)	(433)
Proceeds from sale of equipment	0	4	0
Net cash used in investing activities	(32,421)	(7,010)	(433)
Cash flows from financing activities:
Proceeds from public offering, net of underwriting discounts	101,653	58,258	0
Proceeds from initial public offering, net of underwriting discounts	0	0	80,213
Payment of costs related to public offerings	(350)	(429)	(2,424)
Payment of dividend to Series A preferred stockholders	0	0	(7,565)
Proceeds from exercise of common stock options	4,899	3,133	1,108
Principal payments on finance lease obligations	(653)
Repayment of long-term debt	0	0	(40,000)
Proceeds from issuance of long-term debt, net of debt issuance costs	0	0	19,616
Net cash provided by financing activities	105,549	60,962	50,948
Effect of foreign exchange rate changes on cash and cash equivalents	623	(1,459)	1,228
Net increase in cash and cash equivalents	64,825	21,172	42,615
Cash and cash equivalents, beginning of period	94,930	73,758	31,143
Cash and cash equivalents, end of period	159,755	94,930	73,758
Supplemental disclosure of cash flow information:
Cash paid for interest	331	46	515
Cash paid for income taxes	356	680	615
Supplemental disclosure of non-cash financing activities:
Finance lease obligations to acquire new office furniture and fixtures and computer hardware	4,475
Accretion of dividends on convertible preferred stock	0	0	357
Conversion of convertible preferred stock to common stock
Supplemental disclosure of non-cash financing activities:
Conversion of convertible stock	0	0	48,207
Conversion of convertible preferred stock warrant to common stock warrant
Supplemental disclosure of non-cash financing activities:
Conversion of convertible stock	$ 0	$ 0	$ 1,191