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	1 Months Ended								12 Months Ended
	Jun. 30, 2015	May. 31, 2015	Apr. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Apr. 30, 2014	Jan. 31, 2014	May. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Beginning balance							29,602,884		58,388,808	29,602,884
Issuance of class A common stock	11,500,000	280,025	23,000,000	100,000	9,200,000	9,200,000	9,775,000	25,875,000	34,780,025	28,275,000
Issuance of restricted class A common stock, net									651,815	490,381
Issuance of deferred stock units									22,602	20,537
Ending balance				58,388,808					93,843,847	58,388,808