Unconsolidated Entities - Investments in Co-Investment Ventures by Region (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Investments in and advances to unconsolidated entities	$ 3,884,766	$ 2,195,782
Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Weighted average ownership percentage in co-investment ventures	28.40%	25.10%
Investments in and advances to unconsolidated entities	3,708,196	2,013,080
Americas [Member] | Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Weighted average ownership percentage in co-investment ventures	21.60%	23.20%
Investments in and advances to unconsolidated entities	1,106,713	1,111,831
Europe [Member] | Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Weighted average ownership percentage in co-investment ventures	39.60%	29.70%
Investments in and advances to unconsolidated entities	2,173,996	722,748
Asia [Member] | Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Weighted average ownership percentage in co-investment ventures	17.20%	19.20%
Investments in and advances to unconsolidated entities	$ 427,487	$ 178,501