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, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net Income									$ 30,671	$ 96,965	$ 77,130
Noncontrolling interests									4,435	735	(1,940)
Net Income Attributable to Common Stockholders	$ 6,636	$ (649)	$ 9,777	$ 19,342	$ 18,879	$ 37,340	$ 19,543	$ 21,938	$ 35,106	$ 97,700	$ 75,190
Shares:
Basic: Weighted-average number of shares outstanding (in shares)									8,797	9,091	8,188
Plus: Incremental shares from assumed conversion of dilutive instruments (in shares)									163	201	245
Diluted: Weighted-average number of shares outstanding (in shares)									8,960	9,292	8,433
Earnings per share—Basic (in $ per share)	$ 0.78	$ (0.07)	$ 1.10	$ 2.16	$ 2.09	$ 4.10	$ 2.14	$ 2.41	$ 3.99	$ 10.75	$ 9.18
Earnings per share—Diluted (in $ per share)	$ 0.76	$ (0.07)	$ 1.08	$ 2.11	$ 2.05	$ 4.02	$ 2.10	$ 2.34	$ 3.92	$ 10.51	$ 8.92