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
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 60,958	$ 51,405
Weighted-average shares outstanding, basic and diluted	108,397,598	94,993,386
Per share amount, basic and diluted	$ 0.56	$ 0.54