Unconsolidated Entities - Summary of Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule Of Equity Method Investments [Line Items]
Other ventures	$ 4,841,225	$ 4,824,724
Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Other ventures	4,631,329	4,665,918
Other Joint Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Other ventures	$ 209,896	$ 158,806