Equity - Schedule of Calculation of Basic and Diluted Earnings Per Share of Class A Common Stock 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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Equity [Abstract]
Net income (loss)	$ 33,466	$ 2,748	$ 46,531	$ (367)
Weighted-average shares outstanding, basic and diluted	47,977,813	12,401,274	43,000,242	7,734,774
Per share amount, basic and diluted	$ 0.70	$ 0.22	$ 1.08	$ (0.05)