Equity - Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Equity [Abstract]
Beginning balance	58,388,808	29,602,884
Issuance of class A common stock	139	9,775,000
Issuance of restricted class A common stock, net	181,049
Issuance of deferred stock units	5,414	4,955
Ending balance	58,575,410	39,382,839