Equity Investments - Activity of the Trust's Equity Investments (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Equity Method Investments [Line Items]
Beginning Balance			$ 134,859,000
Investment in equity investments			12,879,000
Equity Income (loss)	13,856,000	12,809,000	26,249,000	14,051,000
Distributions			(34,900,000)
Sales Price			(26,000)	(2,297,000)
Ending Balance	139,061,000		139,061,000
Sealy [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			8,104,000
Investment in equity investments
Equity Income (loss)			(363,000)
Distributions
Sales Price
Ending Balance	7,741,000		7,741,000
Vintage Housing Holding LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			30,534,000
Investment in equity investments
Equity Income (loss)			7,142,000
Distributions			(3,970,000)
Sales Price
Ending Balance	33,706,000		33,706,000
WRT-Elad One South State Equity LP [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			460,000
Investment in equity investments			1,013,000
Equity Income (loss)			(1,473,000)
Distributions
Sales Price
Ending Balance
WRT-Fenway Wateridge LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			1,522,000
Investment in equity investments			161,000
Equity Income (loss)			133,000
Distributions
Sales Price
Ending Balance	1,816,000		1,816,000
701 7th WRT Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			28,735,000
Investment in equity investments			7,745,000
Equity Income (loss)			2,375,000
Distributions			(1,866,000)
Sales Price
Ending Balance	36,989,000		36,989,000
WRT-Elad One South State Lender Lp [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			24,644,000
Investment in equity investments
Equity Income (loss)			2,988,000
Distributions			(3,114,000)
Sales Price
Ending Balance	24,518,000		24,518,000
WRT-Stamford LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			8,501,000
Investment in equity investments
Equity Income (loss)			701,000
Distributions			(286,000)
Sales Price
Ending Balance	8,916,000		8,916,000
10 Metrotech Loan LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			10,845,000
Investment in equity investments
Equity Income (loss)			3,284,000
Distributions			(14,118,000)
Sales Price
Ending Balance	11,000		11,000
RE CDO Management LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			1,779,000
Investment in equity investments
Equity Income (loss)			3,710,000
Distributions			(4,496,000)
Sales Price
Ending Balance	993,000		993,000
Mentor Retail LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			551,000
Investment in equity investments
Equity Income (loss)			45,000
Distributions
Sales Price
Ending Balance	596,000		596,000
Concord Debt Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance
Investment in equity investments
Equity Income (loss)			3,041,000
Distributions			(3,041,000)
Sales Price
Ending Balance
CDH CDO LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance
Investment in equity investments
Equity Income (loss)			415,000
Distributions			(402,000)
Sales Price			(13,000)
Ending Balance
CDH CDO LLC (1) [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			322,000
Investment in equity investments
Equity Income (loss)			4,274,000
Distributions			(402,000)
Sales Price			(13,000)
Ending Balance	4,181,000		4,181,000
Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			14,880,000
Investment in equity investments
Equity Income (loss)			(17,000)
Distributions			(158,000)
Ending Balance	14,705,000		14,705,000
Atrium Mall LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance
Investment in equity investments			3,935,000
Equity Income (loss)			(31,000)
Distributions
Sales Price
Ending Balance	3,904,000		3,904,000
WRT - ROIC Lakeside Eagle LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance
Investment in equity investments			25,000
Equity Income (loss)			(22,000)
Distributions
Sales Price
Ending Balance	3,000		3,000
Socal Office Portfolio Loan LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			8,000
Investment in equity investments
Equity Income (loss)			(2,000)
Distributions			(6,000)
Sales Price
Ending Balance
Concord Debt Holdings LLC (1) [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance			3,974,000
Investment in equity investments
Equity Income (loss)			49,000
Distributions			(3,041,000)
Sales Price
Ending Balance	$ 982,000		$ 982,000