Quarterly Financial Information (Unaudited) - Summary of Selected Unaudited Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 44,320	$ 40,627	$ 38,779	$ 36,843	$ 34,842	$ 32,254	$ 31,684	$ 30,471	$ 160,569	$ 129,251	$ 106,615
Gross profit	29,900	26,638	25,624	24,247	22,700	19,397	19,655	18,322	106,409	80,074	66,198
Net loss	$ (7,917)	$ (8,755)	$ (8,985)	$ (5,896)	$ (12,736)	$ (9,865)	$ (9,211)	$ (9,195)	$ (31,553)	$ (41,007)	$ (32,872)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.21)	$ (0.63)	$ (0.69)	$ (0.45)	$ (0.99)	$ (0.77)	$ (0.74)	$ (0.74)	$ (1.61)	$ (3.24)	$ (2.72)