Equity - Schedule of Basic and Diluted Earnings Per Share, or EPS, Based on Weighted-Average of Both Restricted and Unrestricted Class A Common Stock Outstanding (Detail) (USD $) In Thousands, except 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, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net income	$ 7,079	$ 8,320	$ 2,748	$ (3,115)	$ 105,189	$ 6,999	$ 2,283	$ 66,553	$ (8,320)	$ 13,722	$ (1,845)	$ 254,585	$ 15,032	$ 181,024	$ 258,142
Weighted-average shares outstanding													18,520,052	2,345,943	2,266,043
Warrants and options outstanding for the purchase of class A common stock														129,351	129,000
Weighted-average shares outstanding, diluted													18,520,052	2,475,294	2,395,043
Per share amount, basic	$ 0.24	$ 0.29	$ 0.22	$ (1.03)	$ 42.21	$ 3.02	$ 1.00	$ 29.14	$ (3.66)	$ 6.04	$ (0.81)	$ 113.47	$ 0.81	$ 77.16	$ 113.92
Per share amount, diluted	$ 0.24	$ 0.29	$ 0.22	$ (1.03)	$ 40.65	$ 2.84	$ 0.93	$ 27.39	$ (3.66)	$ 5.69	$ (0.81)	$ 110.36	$ 0.81	$ 73.13	$ 107.78