CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (19,765)	$ (8,322)	$ (30,338)	$ (15,785)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	1,131	971	2,273	1,874
Stock-based compensation expense	14,894	8,513	24,830	16,706
Provision for doubtful accounts	319	233	359	46
Amortization (accretion) of premiums and discounts on marketable securities, net	112	(23)	213	(104)
Amortization of debt discount and issuance costs	2,213	0	4,410	0
Deferred income tax	(131)	(28)	(131)	(46)
Changes in assets and liabilities:
Accounts receivable	3,847	3,133	18,112	17,951
Deferred commissions	(2,166)	(3,833)	(1,563)	(5,862)
Operating lease right-of-use asset	875	556	1,973	1,224
Other receivables	58	161	(195)	(53)
Prepaid expenses and other	(890)	(310)	(2,845)	(3,546)
Other assets	(609)	58	(683)	(1,406)
Accounts payable	(1,692)	1,206	(3,074)	(356)
Deferred revenue	(3,640)	8,295	(4,868)	10,282
Operating lease liability	(1,178)	(813)	(2,323)	(1,468)
Accrued expenses and other liabilities	13,735	8,966	5,712	4,425
Net cash provided by operating activities	7,113	18,763	11,862	23,882
Cash flows from investing activities
Purchase of property and equipment	(696)	(454)	(1,384)	(2,197)
Purchase of marketable securities	(16,457)	(18,562)	(37,289)	(40,717)
Sale of marketable securities	0	0	11,423	0
Maturities of marketable securities	13,062	11,500	26,037	18,890
Purchase of intangible assets	(74)	(577)	(151)	(661)
Net cash used in investing activities	(4,165)	(8,093)	(1,364)	(24,685)
Cash flows from financing activities
Proceeds from option exercises	6,664	5,498	9,458	16,553
Taxes paid related to net share settlements of stock-based compensation awards	(732)	0	(2,111)	(390)
Proceeds from shares issued in connection with employee stock purchase plan	0	0	3,660	2,149
Principal payments on financing obligations	(328)	(301)	(648)	(595)
Net cash provided by financing activities	5,604	5,197	10,359	17,717
Effect of foreign exchange rates on cash	135	110	(478)	215
Net increase in cash and cash equivalents	8,687	15,977	20,379	17,129
Cash and cash equivalents at beginning of period	393,434	78,736	381,742	77,584
Cash and cash equivalents at end of period	402,121	94,713	402,121	94,713
Supplemental cash flow disclosure
Cash paid for interest	382	422	2,702	886
Cash paid for income taxes, net of refunds	227	28	385	261
Supplemental disclosure of noncash investing and financing activities
Allowance for tenant improvements	25	0	149	0
Purchases of property and equipment, accrued but not paid	$ 0	$ 444	$ 0	$ 444