Unconsolidated Entities - Earnings on Investment in Co-Investment Ventures (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	$ 29,746	$ 24,768
Private capital revenue	45,310	33,635
Unconsolidated Co-Investment Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	28,831	24,295
Total Investment management revenue	44,822	33,432
Private capital revenue	45,529	34,479
Unconsolidated Co-Investment Ventures [Member] | Development management and other income - Europe [Member]
Schedule of Equity Method Investments [Line Items]
Total Investment management revenue	707	1,047
Unconsolidated Co-Investment Ventures [Member] | Americas [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	(329)	14,268
Total Investment management revenue	14,325	16,077
Unconsolidated Co-Investment Ventures [Member] | Europe [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	25,495	7,542
Total Investment management revenue	21,700	10,613
Unconsolidated Co-Investment Ventures [Member] | Asia [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	3,665	2,485
Total Investment management revenue	$ 8,797	$ 6,742