Quarterly Financial Data (unaudited) - Schedule of Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 39,533	$ 35,901	$ 34,752	$ 31,068	$ 31,978	$ 27,195	$ 26,579	$ 25,842	$ 141,254	$ 111,594	$ 90,918
Gross profit	32,690	29,439	28,895	25,812	26,592	23,102	22,410	21,543	116,836	93,647	76,148
Operating loss	(3,659)	(2,240)	(1,795)	(3,019)	(905)	(906)	(235)	(278)	(10,713)	(2,324)	(1,274)
Net loss	$ (3,131)	$ (2,019)	$ (2,328)	$ (3,499)	$ (15,105)	$ (7,984)	$ (2,959)	$ (1,887)	$ (10,977)	$ (27,935)	$ (9,701)
Net loss per common share (in dollars per share)	$ (0.12)	$ (0.08)	$ (0.09)	$ (0.15)	$ (0.69)	$ (1.68)	$ (0.62)	$ (0.41)	$ (0.43)	$ (3.09)	$ (2.10)