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
	Mar. 31, 2014	Mar. 31, 2013
Equity [Abstract]
Net income (loss)	$ 13,065	$ (3,115)
Weighted-average shares outstanding, basic and diluted	37,967,365	3,016,425
Per share amount, basic and diluted	$ 0.34	$ (1.03)