Net Income (Loss) Per Share - Calculation of Basic and Diluted Weighted-Average Number of Shares of Common Stock and EPS (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, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic:
Net income, basic					$ 31,762	$ 18,826	$ 8,525
Net income, shares, basic					33,211	19,999	17,479
Net income, per shares, basic	$ 1.81	$ 0.20	$ (0.95)	$ (0.13)	$ 0.96	$ 0.94	$ 0.49
Weighted-average number of shares of common stock-diluted:
Restricted stock and performance unit awards					113	88	200
Diluted:
Net income, diluted					$ 31,762	$ 18,826	$ 8,525
Net income, shares, diluted					33,324	20,087	17,679
Net income, per shares, diluted	$ 1.80	$ 0.20	$ (0.95)	$ (0.13)	$ 0.95	$ 0.94	$ 0.48