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, 2019	Mar. 31, 2018
Basic:
Net income (loss)	$ 21,663	$ (6,170)
Weighted average common shares outstanding (in shares)	20,585	20,506
Net income (loss) per share (in dollars per share)	$ 1.05	$ (0.30)
Diluted:
Unvested restricted stock and DSU's	0	0
Employee stock options	0	0
Weighted average common shares outstanding	$ 20,585	$ 20,506
Net income (loss) per dilutive share	$ 0	$ 0