Unconsolidated Entities - Earnings on Investment in Co-Investment Ventures (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	$ 31,676	$ 59,935	$ 23,678
Private capital revenue	126,779	137,619	122,526
Unconsolidated co-investment ventures [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	25,703	49,326	10,548
Total private capital revenue	125,185	127,200	116,751
Private capital revenue	125,720	133,143	124,164
Unconsolidated co-investment ventures [Member] | Development management and other income - Europe [Member]
Schedule of Equity Method Investments [Line Items]
Total private capital revenue	535	5,943	7,413
Unconsolidated co-investment ventures [Member] | Americas [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	(7,843)	22,709	(13,243)
Total private capital revenue	68,142	67,293	61,159
Unconsolidated co-investment ventures [Member] | Europe [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	31,174	25,709	28,024
Total private capital revenue	37,173	45,758	54,834
Unconsolidated co-investment ventures [Member] | Asia [Member]
Schedule of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	2,372	908	(4,233)
Total private capital revenue	$ 19,870	$ 14,149	$ 758