Equity Investments - Activity of the Trust's Equity Investments (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 01, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Schedule of Equity Method Investments [Line Items]
Beginning Balance				$ 134,859
Investment in equity investments	5,850			5,819	33,546
Equity Income (loss)		4,524	818	12,393	1,242
Distributions				(10,731)	(4,788)
Sales Price				(26)	(2,297)
Ending Balance		141,645		141,645
Sealy [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				8,104
Equity Income (loss)				(233)
Ending Balance		7,871		7,871
Vintage Housing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				30,534
Equity Income (loss)				4,617
Distributions				(2,265)
Ending Balance		32,886		32,886
WRT-Elad One South State Equity LP [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				460
Investment in equity investments				865
Equity Income (loss)				(1,325)
WRT-Elad One South State Lender LP [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				24,644
Equity Income (loss)				1,935
Distributions				(2,965)
Ending Balance		23,614		23,614
WRT-Fenway Wateridge LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				1,522
Investment in equity investments				117
Equity Income (loss)				83
Ending Balance		1,722		1,722
701 7th WRT Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				28,735
Investment in equity investments				1,742
Equity Income (loss)				1,320
Distributions				(1,195)
Ending Balance		30,602		30,602
WRT-Stamford [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				8,501
Equity Income (loss)				445
Distributions				(173)
Ending Balance		8,773		8,773
10 Metrotech Loan LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				10,845
Equity Income (loss)				608
Distributions				(608)
Ending Balance		10,845		10,845
RE CDO Management LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				1,779
Equity Income (loss)				3,761
Distributions				(4,479)
Ending Balance		1,061		1,061
Mentor Retail LLC [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				551
Equity Income (loss)				33
Ending Balance		584		584
Concord Debt Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Income (loss)				71
Distributions				(71)
CDH CDO LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Income (loss)				150
Distributions				(137)
Sales Price				(13)
CDH CDO LLC (1) [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				322
Equity Income (loss)				907
Distributions				(137)
Sales Price				(13)
Ending Balance		1,079		1,079
Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				14,880
Equity Income (loss)				9
Distributions				(158)
Ending Balance		14,731		14,731
Atrium Mall LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment in equity investments				3,935
Ending Balance		3,935		3,935
WRT - ROIC Lakeside Eagle LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment in equity investments				25
Equity Income (loss)				(15)
Ending Balance		10		10
SoCal Office Portfolio Loan [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				8
Equity Income (loss)				(2)
Distributions				(6)
Concord Debt Holdings LLC (1) [Member]
Schedule of Equity Method Investments [Line Items]
Beginning Balance				3,974
Equity Income (loss)				29
Distributions				(71)
Ending Balance		$ 3,932		$ 3,932