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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 72,312	$ 50,613	$ 133,271	$ 102,018
Weighted-average shares outstanding, basic and diluted	109,069,078	95,005,873	108,735,193	94,999,664
Per share amount, basic and diluted	$ 0.66	$ 0.53	$ 1.23	$ 1.07