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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 53,375	$ 64,794	$ 63,081	$ 57,047	$ 65,264	$ 66,888	$ 29,284	$ 35,393	$ 238,297	$ 196,829	$ 90,045
Weighted-average shares outstanding, basic and diluted									94,165,351	81,740,227	48,394,478
Per share amount, basic and diluted	$ 0.57	$ 0.69	$ 0.67	$ 0.61	$ 0.70	$ 0.72	$ 0.36	$ 0.60	$ 2.53	$ 2.41	$ 1.86