Equity Investments - Activity of the Trust's Equity Investments (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2013
Vintage Housing Holding LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment lag Period	1 month
WRT-Elad One South State Equity LP [Member]
Schedule of Equity Method Investments [Line Items]
Investment lag Period	1 month
WRT-Elad One South State Lender LP [Member]
Schedule of Equity Method Investments [Line Items]
Investment lag Period	1 month
WRT-Fenway Wateridge LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment lag Period	1 month
701 7th WRT Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment lag Period	3 months