Unconsolidated Entities - Earnings on Investment in Co-Investment Ventures (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	$ 33,557	$ 28,514	$ 106,383	$ 79,411
Strategic capital revenue	44,176	54,070	133,247	175,714
Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	32,617	27,194	103,704	77,079
Total strategic capital revenue	43,510	53,765	131,284	174,680
Strategic capital revenue	45,357	55,443	136,317	177,939
Unconsolidated Co-Investment Ventures [Member] | Development Management Income [Member]
Schedule Of Equity Method Investments [Line Items]
Total strategic capital revenue	1,847	1,678	5,033	3,259
Unconsolidated Co-Investment Ventures [Member] | Americas [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	10,558	8,863	25,116	8
Total strategic capital revenue	14,098	18,449	45,073	80,004
Unconsolidated Co-Investment Ventures [Member] | Europe [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	20,871	14,653	69,685	66,890
Total strategic capital revenue	20,652	24,713	60,046	65,866
Unconsolidated Co-Investment Ventures [Member] | Asia [Member]
Schedule Of Equity Method Investments [Line Items]
Earnings from unconsolidated entities, net	1,188	3,678	8,903	10,181
Total strategic capital revenue	$ 8,760	$ 10,603	$ 26,165	$ 28,810