Equity - Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units (Detail) - Class A Common Stock [Member] - shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Beginning balance	58,388,808	29,602,884
Issuance of class A common stock	34,780,443	28,175,003
Issuance of restricted class A common stock, net	162,531
Issuance of deferred stock units	16,288	15,104
Ending balance	93,348,070	57,792,991