Equity - Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units (Detail) - shares	1 Months Ended	9 Months Ended
	May 31, 2013	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
Beginning balance		93,843,847	58,388,808
Issuance of class A common stock	25,875,000	812	34,780,443
Issuance of restricted class A common stock, net		209,798	162,531
Issuance of deferred stock units		20,850	16,288
Ending balance		94,075,307	93,348,070