Equity Investments - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended				1 Months Ended		6 Months Ended	1 Months Ended	6 Months Ended		1 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	May 30, 2013 Sealy [Member]	Jun. 30, 2013 Concord Debt Holdings (1) [Member]	Feb. 25, 2013 Concord Debt Holdings LLC [Member]	Feb. 25, 2013 Lex-Win [Member]	Feb. 25, 2013 CDH CDO LLC [Member]	Jun. 30, 2013 Vintage Housing LLC [Member]	Feb. 18, 2013 WRT-Elad One South State Equity LP [Member]	Jun. 30, 2013 WRT-Elad One South State Equity LP [Member]	Jun. 30, 2013 WRT Elad [Member]	Mar. 08, 2013 RE CDO Management LLC [Member]	Feb. 20, 2013 RE CDO Management LLC [Member]
Schedule of Equity Method Investments [Line Items]
Increase in occupancy of lease renewal	72.00%	70.00%
Future interest									5.00%	5.00%
Future interest									70.00%	70.00%
Fee to be paid by the borrower									$ 1,400,000	$ 1,400,000
Additional increase in indirect future interest									6.00%	6.00%
Interests acquired				5,288,000							11,719,000
Percentage of the ownership					17.00%
Acquisition Price						25,000
sales price of the trust							12,500
Gain on sale of interest							12,500
Loss on sale of interest							123,000
Sale of subordinated interests												6,240,000	2,750,000
Transfer of collateral management agreement													0
Aggregate amount received from sales												4,416,000
Carrying value of investment	$ 391,000,000	$ 370,436,000	$ 0
Investment lag Period								1 month		1 month