Earnings Per Share - Schedule of Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income									$ 48,763	$ 30,671	$ 96,965
Noncontrolling interests									(261)	4,435	735
Net Income Attributable to Common Stockholders	$ 12,426	$ 15,625	$ 8,088	$ 12,363	$ 6,636	$ (649)	$ 9,777	$ 19,342	$ 48,502	$ 35,106	$ 97,700
Shares:
Basic: Weighted-average number of shares outstanding (in shares)									7,648	8,797	9,091
Plus: Incremental shares from assumed conversion of dilutive instruments (in shares)									174	163	201
Diluted: Weighted-average number of shares outstanding (in shares)									7,822	8,960	9,292
Earnings per share—basic (in $ per share)	$ 1.94	$ 2.04	$ 0.99	$ 1.48	$ 0.78	$ (0.07)	$ 1.10	$ 2.16	$ 6.34	$ 3.99	$ 10.75
Earnings per share—diluted (in $ per share)	$ 1.87	$ 1.99	$ 0.97	$ 1.45	$ 0.76	$ (0.07)	$ 1.08	$ 2.11	$ 6.20	$ 3.92	$ 10.51