Earnings (Loss) 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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income (Loss)									$ 39,939	$ 48,763	$ 30,671
Noncontrolling interests									(2,927)	(261)	4,435
Net Income (Loss) Attributable to Stockholders									37,012	48,502	35,106
Preferred stockholder dividends									(8,336)	0	0
Net Income (Loss) Attributable to Common Stockholders	$ 3,414	$ 16,708	$ (2,389)	$ 10,943	$ 12,426	$ 15,625	$ 8,088	$ 12,363	$ 28,676	$ 48,502	$ 35,106
Shares (in thousands):
Basic: Weighted-average number of shares outstanding (in shares)									7,013	7,648	8,797
Plus: Incremental shares from assumed conversion of dilutive instruments (in shares)									234	174	163
Diluted: Weighted-average number of shares outstanding (in shares)									7,247	7,822	8,960
Earnings per share—basic (in $ per share)	$ 0.48	$ 2.32	$ (0.34)	$ 1.67	$ 1.94	$ 2.04	$ 0.99	$ 1.48	$ 4.09	$ 6.34	$ 3.99
Earnings per share—diluted (in $ per share)	$ 0.46	$ 2.21	$ (0.34)	$ 1.62	$ 1.87	$ 1.99	$ 0.97	$ 1.45	$ 3.96	$ 6.20	$ 3.92