Earnings Per Share - Schedule of Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net Income									$ 77,130	$ 37,773	$ 145,420
Noncontrolling interests									(1,940)	(101)
Preferred stockholder dividends											(9,482)
Allocation of earnings to preferred stockholders										(64)	(24,260)
Net Income Attributable to Common Stockholders	$ 24,756	$ 21,089	$ 15,385	$ 13,960	$ 12,213	$ 11,642	$ 8,367	$ 5,386	$ 75,190	$ 37,608	$ 111,678
Shares:
Basic: Weighted-average number of shares outstanding									8,188	7,727	6,211
Plus: Incremental shares from assumed conversion of dilutive instruments									245	346	623
Diluted: Weighted-average number of shares outstanding									8,433	8,073	6,834
Earnings per share-Basic	$ 2.72	$ 2.64	$ 1.97	$ 1.79	$ 1.56	$ 1.48	$ 1.08	$ 0.72	$ 9.18	$ 4.87	$ 17.98
Earnings per share-Diluted	$ 2.65	$ 2.56	$ 1.91	$ 1.73	$ 1.50	$ 1.43	$ 1.04	$ 0.68	$ 8.92	$ 4.66	$ 16.34