Stockholders' Equity - Diluted Earnings 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
Equity [Abstract]
Net income (loss) attributable to common stockholders									$ 44,512	$ (1,705)	$ 6,785
Weighted average number of common shares outstanding (in shares)									30,277	29,942	29,530
Dilutive effect of restricted stock grants after application of the treasury stock method (in shares)									310	0	348
Dilutive shares outstanding (in shares)									30,587	29,942	29,878
Basic (in dollars per share)	$ 0.29	$ 0.42	$ 0.44	$ 0.33	$ (0.24)	$ 0.16	$ 0.00	$ 0.02	$ 1.47	$ (0.06)	$ 0.23
Diluted (in dollars per share)	$ 0.29	$ 0.41	$ 0.43	$ 0.32	$ (0.24)	$ 0.16	$ 0.00	$ 0.02	$ 1.46	$ (0.06)	$ 0.23