Unconsolidated Entities - Summary of Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Other ventures	$ 4,559,721	$ 4,824,724
Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Other ventures	4,381,650	4,665,918
Other Joint Ventures [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Other ventures	$ 178,071	$ 158,806