Selected Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Selected Quarterly Financial Information [Abstract]
Revenue	$ 103,356	$ 92,392	$ 81,690	$ 79,366	$ 91,104	$ 81,748	$ 81,102	$ 68,586	$ 356,804	$ 322,540	$ 292,894
Gross profit	31,202	26,199	15,675	15,737	22,586	18,933	15,472	9,182	88,813	66,173	61,479
Net income (loss)	$ 2,069	$ 2,272	$ (7,326)	$ (14,091)	$ (6,729)	$ (8,125)	$ (10,537)	$ (18,246)	$ (17,076)	$ (43,637)	$ (53,333)
Basic net income (loss) per share (USD per share)	$ 0.04	$ 0.05	$ (0.16)	$ (0.30)	$ (0.15)	$ (0.18)	$ (0.24)	$ (0.41)	$ (0.36)	$ (0.97)	$ (1.23)
Diluted net income (loss) per share (USD per share)	$ 0.04	$ 0.05	$ (0.16)	$ (0.30)	$ (0.15)	$ (0.18)	$ (0.24)	$ (0.41)	$ (0.36)	$ (0.97)	$ (1.23)
Weighted average shares used to compute basic net income (loss) per share (in shares)	48,358	47,666	46,754	46,414	46,150	45,476	44,665	44,259	47,304	45,144	43,431
Weighted average shares used to compute diluted net income (loss) per share (in shares)	50,238	48,615	46,754	46,414	46,150	45,476	44,665	44,259	47,304	45,144	43,431