Net Income (Loss) Per Share - Calculations of 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 income (loss)	$ (6,170)	$ (22,097)
Weighted average common shares outstanding (in shares)	20,506	20,380
Net income (loss) per share (in dollars per share)	$ (0.30)	$ (1.08)
Diluted:
Weighted average common shares outstanding	$ 20,506	$ 20,380
Net loss for dilutive share computation	$ 0	$ 0