Quarterly Financial Information (Unaudited) - Summary of Condensed Consolidated Statements of Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 16,839	$ 16,694	$ 19,203	$ 20,678	$ 19,469	$ 19,653	$ 18,848	$ 22,841	$ 73,414	$ 80,811
Gross profit	3,690	3,359	3,261	5,200	3,616	4,380	3,873	6,253	15,510	18,122
Income (loss) from operations	(5,603)	(2,132)	(3,718)	(2,478)	(4,297)	(2,546)	(2,619)	41	(13,931)	(9,421)
Net income (loss)	$ (5,533)	$ (2,087)	$ (3,683)	$ (2,434)	$ (4,232)	$ (2,468)	$ (2,560)	$ 202	$ (13,737)	$ (9,058)
Basic income (loss) per share	$ (0.43)	$ (0.16)	$ (0.29)	$ (0.19)	$ (0.33)	$ (0.20)	$ (0.20)	$ 0.02	$ (1.08)	$ (0.72)
Diluted income (loss) per share	$ (0.43)	$ (0.16)	$ (0.29)	$ (0.19)	$ (0.33)	$ (0.20)	$ (0.20)	$ 0.02	$ (1.08)	$ (0.72)
Shares used in per share calculations:
Basic	12,755	12,721	12,697	12,673	12,640	12,607	12,577	12,550	12,712	12,594
Diluted	12,755	12,721	12,697	12,673	12,640	12,607	12,577	12,848	12,712	12,594