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		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net income	$ 57,722	$ 64,794	$ 159,741	$ 184,921
Weighted-average shares outstanding, basic and diluted	95,013,087	94,071,537	95,004,188	94,067,923
Per share amount, basic and diluted	$ 0.61	$ 0.69	$ 1.68	$ 1.97