Net Loss Per Share - Reconciliation of Net Income (Loss) and Weighted Average Shares used in Computing Basic and Diluted Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic net loss per share:
Net loss applicable to common shares	$ (4,219)	$ (2,687)
Weighted average common shares outstanding	14,137	12,971
Basic net loss per share of common stock	$ (0.30)	$ (0.21)
Diluted net loss per share:
Net loss applicable to common shares	$ (4,219)	$ (2,687)
Weighted average common shares outstanding	14,137	12,971
Dilutive effects of stock options	0	0
Weighted average common shares, assuming dilutive effect of stock options	14,137	12,971
Diluted net loss per share of common stock	$ (0.30)	$ (0.21)