Investment In Unconsolidated Subsidiaries - Additional information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Non-cash write downs of investments	$ 4,100,000	$ 3,900,000	$ 5,600,000
Global Investment Management [Member]
Schedule of Equity Method Investments [Line Items]
Non-cash write downs of investments		3,800,000	5,500,000
Global Investment Management [Member] | Investment management, property management, brokerage and other professional services [Member]
Schedule of Equity Method Investments [Line Items]
Revenues from unconsolidated subsidiaries	252,600,000	190,000,000	104,000,000
Development Services [Member]
Schedule of Equity Method Investments [Line Items]
Non-cash write downs of investments		100,000	100,000
Development Services [Member] | Investment management, property management, brokerage and other professional services [Member]
Schedule of Equity Method Investments [Line Items]
Revenues from unconsolidated subsidiaries	17,500,000	21,200,000	5,700,000
Global Investment Management and Development Services segments [Member]
Schedule of Equity Method Investments [Line Items]
Non-cash write downs of investments	$ 4,100,000	$ 3,900,000	$ 5,600,000