Unconsolidated Entities - Earnings on Investment in Co-Investment Ventures (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	$ 31,042	$ 29,746
Strategic capital revenue	42,025	45,310
Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	30,236	28,831
Total strategic capital revenue	41,303	44,822
Strategic capital revenue	42,943	45,529
Unconsolidated Co-Investment Ventures [Member] | Development Management and Other Income [Member]
Schedule Of Equity Method Investments [Line Items]
Total strategic capital revenue	1,640	707
Unconsolidated Co-Investment Ventures [Member] | Americas [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	4,798	(329)
Total strategic capital revenue	14,361	14,325
Unconsolidated Co-Investment Ventures [Member] | Europe [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	21,508	25,495
Total strategic capital revenue	18,393	21,700
Unconsolidated Co-Investment Ventures [Member] | Asia [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	3,930	3,665
Total strategic capital revenue	$ 8,549	$ 8,797