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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 78,165	$ 57,722	$ 211,436	$ 159,741
Weighted-average shares outstanding, basic and diluted	116,203,140	95,013,087	111,251,864	95,004,188
Per share amount, basic and diluted	$ 0.67	$ 0.61	$ 1.90	$ 1.68