Equity Investments - Activity of the Trust's Equity Investments (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Oct. 07, 2013
Schedule of Equity Method Investments [Line Items]
Ending Balance	$ 149,085,000	$ 134,859,000	$ 162,142,000	$ 0
Beginning Balance	134,859,000	162,142,000		0
Investment in equity investments	32,424,000	85,540,000
Equity Income (loss)	22,641,000	14,843,000	(12,712,000)
Distributions	(40,813,000)	(105,619,000)
Sales Price	(26,000)	22,047,000
Sealy [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	7,635,000	8,104,000
Beginning Balance	8,104,000	11,348,000
Investment in equity investments
Equity Income (loss)	(469,000)	(3,199,000)
Distributions		(45,000)
Sales Price
Vintage Housing Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	34,153,000	30,534,000
Beginning Balance	30,534,000	29,887,000
Investment in equity investments		2,067,000
Equity Income (loss)	9,174,000	4,603,000
Distributions	(5,555,000)	(6,023,000)
Sales Price
WRT-Elad One South State Equity LP [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance		460,000
Beginning Balance	460,000
Investment in equity investments	2,358,000	2,838,000
Equity Income (loss)	(2,818,000)	(2,378,000)
Distributions
Sales Price
WRT-One South State Lender LP [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	23,661,000	24,644,000
Beginning Balance	24,644,000	10,150,000
Investment in equity investments		11,213,000
Equity Income (loss)	4,133,000	3,281,000
Distributions	(5,116,000)
Sales Price
WRT-Stamford LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	9,064,000	8,501,000
Beginning Balance	8,501,000
Investment in equity investments		8,036,000
Equity Income (loss)	930,000	769,000
Distributions	(367,000)	(304,000)
Sales Price
10 Metrotech Loan LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	11,000	10,845,000
Beginning Balance	10,845,000
Investment in equity investments		10,915,000
Equity Income (loss)	3,284,000	335,000
Distributions	(14,118,000)	(405,000)
Sales Price
RE CDO Management LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	992,000	1,779,000
Beginning Balance	1,779,000	1,296,000
Investment in equity investments		550,000
Equity Income (loss)	3,709,000	67,000
Distributions	(4,496,000)	(134,000)
Sales Price
Concord Debt Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance
Beginning Balance
Investment in equity investments
Equity Income (loss)	3,072,000	422,000
Distributions	(3,072,000)	(422,000)
Sales Price
CDH CDO LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance
Beginning Balance
Investment in equity investments
Equity Income (loss)	1,033,000	1,715,000
Distributions	(1,020,000)	(1,715,000)
Sales Price	(13,000)
Concord Debt Holdings LLC (1) [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	966,000	3,974,000
Beginning Balance	3,974,000
Investment in equity investments		4,501,000
Equity Income (loss)	64,000	(456,000)
Distributions	(3,072,000)	(71,000)
Sales Price
CDH CDO LLC (1) [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	4,215,000	322,000
Beginning Balance	322,000
Investment in equity investments		2,500,000
Equity Income (loss)	4,926,000	(997,000)
Distributions	(1,020,000)	(1,181,000)
Sales Price	(13,000)
Mentor Retail LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	635,000	551,000
Beginning Balance	551,000
Investment in equity investments		505,000
Equity Income (loss)	84,000	46,000
Distributions
Sales Price
701 7th WRT Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	55,259,000	28,735,000
Beginning Balance	28,735,000
Investment in equity investments	25,913,000	29,025,000
Equity Income (loss)	3,424,000
Distributions	(2,813,000)	(290,000)
Sales Price
WRT-Fenway Wateridge LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	1,898,000	1,522,000
Beginning Balance	1,522,000
Investment in equity investments	193,000	1,522,000
Equity Income (loss)	183,000
Distributions
Sales Price
Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	6,751,000	14,880,000
Beginning Balance	14,880,000	27,145,000
Investment in equity investments		11,833,000
Equity Income (loss)	(7,971,000)	33,000
Distributions	(158,000)	(4,116,000)
Sales Price		20,015,000
WRT - ROIC Lakeside Eagle LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance
Beginning Balance		7,000
Investment in equity investments	25,000	35,000
Equity Income (loss)	(25,000)	(42,000)
Distributions
Sales Price
Socal Office Portfolio Loan LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance		8,000
Beginning Balance	8,000	72,626,000
Investment in equity investments
Equity Income (loss)	(2,000)	9,706,000
Distributions	(6,000)	(82,324,000)
Sales Price		2,032,000
Atrium Mall LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance	3,845,000
Beginning Balance
Investment in equity investments	3,935,000
Equity Income (loss)	(90,000)
Distributions
Sales Price
WRT - ROIC Riverside LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance
Beginning Balance		7,883,000
Investment in equity investments
Equity Income (loss)		706,000
Distributions		(8,589,000)
Sales Price
F-II Co Invest LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ending Balance
Beginning Balance		1,800,000
Investment in equity investments
Equity Income (loss)		232,000
Distributions
Sales Price