CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Total revenue	$ 68,618	$ 66,155	$ 65,275	$ 60,304	$ 60,216	$ 54,948	$ 59,883	$ 51,696	$ 260,352	$ 226,743	$ 176,737
Cost of revenue:
Total cost of revenue	22,773	23,951	23,051	24,066	22,210	20,092	21,574	21,049	93,841	84,925	64,597
Gross profit	45,845	42,204	42,224	36,238	38,006	34,856	38,309	30,647	166,511	141,818	112,140
Operating expenses:
Sales and marketing	31,254	27,603	29,992	28,591	30,177	25,467	27,384	22,964	117,440	105,992	81,966
Research and development	15,625	15,697	12,765	13,956	12,332	11,737	10,785	9,870	58,043	44,724	34,835
General and administrative	12,028	11,191	9,261	9,016	8,799	12,537	8,425	8,060	41,496	37,821	27,150
Total operating expenses	58,907	54,491	52,018	51,563	51,308	49,741	46,594	40,894	216,979	188,537	143,951
Operating loss	(13,062)	(12,287)	(9,794)	(15,325)	(13,302)	(14,885)	(8,285)	(10,247)	(50,468)	(46,719)	(31,811)
Other (income) expense:
Other (income) expense, net	(2,822)	2,262	(79)	(302)	510	110	2,593	(918)	(941)	2,295	(2,038)
Interest expense	131	96	69	71	64	67	54	13	367	198	473
Total other (income) expense	(2,691)	2,358	(10)	(231)	574	177	2,647	(905)	(574)	2,493	(1,565)
Loss before income taxes	(10,371)	(14,645)	(9,784)	(15,094)	(13,876)	(15,062)	(10,932)	(9,342)	(49,894)	(49,212)	(30,246)
Income tax expense	426	5	267	122	27	(34)	35	211	820	239	761
Net loss	(10,797)	(14,650)	(10,051)	(15,216)	(13,903)	(15,028)	(10,967)	(9,553)	(50,714)	(49,451)	(31,007)
Accretion of dividends on convertible preferred stock									0	0	357
Net loss attributable to common stockholders									$ (50,714)	$ (49,451)	$ (31,364)
Net loss per share attributable to common stockholders:
Basic and diluted (in usd per share)									$ (0.77)	$ (0.80)	$ (0.63)
Weighted average common shares outstanding:
Basic and diluted (in shares)									65,479,327	62,140,684	49,529,833
Subscriptions
Revenue:
Total revenue	42,108	37,774	36,860	34,557	35,108	30,905	33,047	26,952	$ 151,299	$ 126,012	$ 91,514
Cost of revenue:
Total cost of revenue	4,993	4,484	4,036	3,585	3,284	3,261	2,824	2,628	17,098	11,997	9,379
Professional services
Revenue:
Total revenue	26,510	28,381	28,415	25,747	25,108	24,043	26,836	24,744	109,053	100,731	85,223
Cost of revenue:
Total cost of revenue	$ 17,780	$ 19,467	$ 19,015	$ 20,481	$ 18,926	$ 16,831	$ 18,750	$ 18,421	$ 76,743	$ 72,928	$ 55,218