Unconsolidated Entities - Earnings on Investment in Co-Investment Ventures (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	$ 21,151	$ 8,421	$ 50,897	$ 33,189
Private capital revenue	76,334	43,608	121,644	77,243
Unconsolidated Co-Investment Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	21,054	7,871	49,885	32,166
Total Strategic capital revenue	76,093	42,911	120,915	76,343
Private capital revenue	76,967	43,244	122,496	77,723
Unconsolidated Co-Investment Ventures [Member] | Development management and other income [Member]
Schedule of Equity Method Investments [Line Items]
Total Strategic capital revenue	874	333	1,581	1,380
Unconsolidated Co-Investment Ventures [Member] | Americas [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	(8,526)	(874)	(8,855)	13,394
Total Strategic capital revenue	47,230	14,818	61,555	30,895
Unconsolidated Co-Investment Ventures [Member] | Europe [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	26,742	8,761	52,237	16,303
Total Strategic capital revenue	19,453	13,854	41,153	24,467
Unconsolidated Co-Investment Ventures [Member] | Asia [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	2,838	(16)	6,503	2,469
Total Strategic capital revenue	$ 9,410	$ 14,239	$ 18,207	$ 20,981