Earnings (Loss) Per Share - Summary of Calculation of Basic and Diluted Earnings (Loss) Per Share (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	Dec. 31, 2016
Numerator
Net Income (Loss)	$ (8,447)	$ 7,589	$ (7,670)	$ (10,814)	$ (11,110)	$ 15,898	$ 12,401	$ 6,651	$ (19,342)	$ 23,840	$ 35,229
Denominator
Weighted average number of shares – basic									47,880	48,153	48,724
Effect of dilutive securities:
Stock options										406	170
Restricted stock and restricted stock units										140	55
Weighted average number of shares – diluted									47,880	48,699	48,949
Earnings (loss) per share – basic	$ (0.18)	$ 0.16	$ (0.16)	$ (0.22)	$ (0.23)	$ 0.33	$ 0.26	$ 0.14	$ (0.40)	$ 0.50	$ 0.72
Earnings (loss) per share – diluted	$ (0.18)	$ 0.16	$ (0.16)	$ (0.22)	$ (0.23)	$ 0.33	$ 0.26	$ 0.14	$ (0.40)	$ 0.49	$ 0.72