Quarterly Financial Information (Unaudited) - Summary of Selected Quarterly Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 7,564	$ 11,455	$ 10,213	$ 8,326	$ 7,259	$ 11,537	$ 6,654	$ 7,016	$ 37,558	$ 32,464	$ 29,226
Gross profit	3,028	5,025	4,643	3,448	2,811	6,437	2,785	2,744	16,144	14,775	15,976
Operating expenses	5,244	4,156	4,976	4,279	2,551	2,851	2,706	2,852	18,655	10,960	10,101
(Loss) income from operations	(2,216)	869	(333)	(831)	260	3,586	79	(108)	(2,511)	3,815	5,875
Change in fair value of common stock warrants						1	70	309	0	(379)	(794)
Net (loss) income	$ (2,069)	$ 953	$ (326)	$ (692)	$ (494)	$ 3,744	$ (10)	$ 152	$ (2,134)	$ 3,390	$ 6,704
Income (loss) per common share:
Basic	$ (0.19)	$ 0.09	$ (0.03)	$ (0.06)	$ (0.05)	$ 0.35	$ 0.00	$ 0.01	$ (0.20)	$ 0.31	$ 0.59
Diluted	$ (0.19)	$ 0.09	$ (0.03)	$ (0.06)	$ (0.05)	$ 0.35	$ (0.01)	$ (0.01)	$ (0.20)	$ 0.27	$ 0.52