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 ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 65,264	$ 66,888	$ 29,284	$ 35,393	$ 21,490	$ 22,024	$ 33,466	$ 13,065	$ 196,829	$ 90,045	$ 15,032
Weighted-average shares outstanding, basic and diluted									81,740,227	48,394,478	18,520,052
Per share amount, basic and diluted	$ 0.70	$ 0.72	$ 0.36	$ 0.60	$ 0.37	$ 0.45	$ 0.70	$ 0.34	$ 2.41	$ 1.86	$ 0.81