Equity Investments - Trust's Carrying Amounts in its Equity Investments (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Sealy [Member]	Dec. 31, 2012 Sealy [Member]	Sep. 30, 2013 Vintage Housing Holding LLC [Member]	Dec. 31, 2012 Vintage Housing Holding LLC [Member]	Sep. 30, 2013 Vintage Housing Holding LLC [Member] VHH LLC [Member]	Dec. 31, 2012 Vintage Housing Holding LLC [Member] VHH LLC [Member]	Sep. 30, 2013 WRT-Elad One South State Equity LP [Member]	Dec. 31, 2012 WRT-Elad One South State Equity LP [Member]	Sep. 30, 2013 WRT-Elad One South State Equity LP [Member] Elad Canada Inc [Member]	Dec. 31, 2012 WRT-Elad One South State Equity LP [Member] Elad Canada Inc [Member]	Sep. 30, 2013 WRT-Elad One South State Lender LP [Member]	Aug. 21, 2013 WRT-Elad One South State Lender LP [Member]	Sep. 30, 2013 WRT-Elad One South State Lender LP [Member] Elad Canada Inc [Member]	Dec. 31, 2012 WRT-Elad One South State Lender LP [Member] Elad Canada Inc [Member]	Sep. 30, 2013 WRT-Stamford LLC [Member]	Dec. 31, 2012 WRT-Stamford LLC [Member]	Sep. 30, 2013 WRT-Stamford LLC [Member] Mack-Cali [Member]	Dec. 31, 2012 WRT-Stamford LLC [Member] Mack-Cali [Member]	Sep. 30, 2013 10 Metrotech Loan LLC [Member]	Dec. 31, 2012 10 Metrotech Loan LLC [Member]	Aug. 31, 2012 10 Metrotech Loan LLC [Member]	Sep. 30, 2013 10 Metrotech Loan LLC [Member] Atrium/Northstar [Member]	Dec. 31, 2012 10 Metrotech Loan LLC [Member] Atrium/Northstar [Member]	Sep. 30, 2013 RE CDO Management LLC [Member]	Dec. 31, 2012 RE CDO Management LLC [Member]	Sep. 30, 2013 RE CDO Management LLC [Member] Atrium Holding [Member]	Dec. 31, 2012 RE CDO Management LLC [Member] Atrium Holding [Member]	Sep. 30, 2013 Mentor Retail LLC [Member]	Dec. 31, 2012 Mentor Retail LLC [Member]	Sep. 30, 2013 Mentor Retail LLC [Member] Freed [Member]	Dec. 31, 2012 Mentor Retail LLC [Member] Freed [Member]	Sep. 30, 2013 Concord Debt Holdings LLC [Member]	Feb. 25, 2013 Concord Debt Holdings LLC [Member]	Dec. 31, 2012 Concord Debt Holdings LLC [Member]	Sep. 30, 2013 Concord Debt Holdings LLC [Member] Inland [Member]	Dec. 31, 2012 Concord Debt Holdings LLC [Member] Inland [Member]	Sep. 30, 2013 CDH CDO LLC [Member]	Dec. 31, 2012 CDH CDO LLC [Member]	Sep. 30, 2013 CDH CDO LLC [Member] Inland [Member]	Dec. 31, 2012 CDH CDO LLC [Member] Inland [Member]	Sep. 30, 2013 Concord Debt Holdings (1) [Member] Inland [Member]	Dec. 31, 2012 Concord Debt Holdings (1) [Member] Inland [Member]	Sep. 30, 2013 CDH CDO (1) [Member] Inland [Member]	Dec. 31, 2012 CDH CDO (1) [Member] Inland [Member]	Sep. 30, 2013 Northwest Atlanta Partners LP [Member] Sealy [Member]	Dec. 31, 2012 Northwest Atlanta Partners LP [Member] Sealy [Member]	Sep. 30, 2013 New Market GP LLC [Member] Sealy [Member]	Dec. 31, 2012 New Market GP LLC [Member] Sealy [Member]	Sep. 30, 2013 Airpark Nashville GP [Member] Sealy [Member]	Dec. 31, 2012 Airpark Nashville GP [Member] Sealy [Member]	Sep. 30, 2013 Brooks Building LLC [Member] Marc Realty [Member]	Dec. 31, 2012 Brooks Building LLC [Member] Marc Realty [Member]	Sep. 30, 2013 High Point Plaza LLC [Member] Marc Realty [Member]	Dec. 31, 2012 High Point Plaza LLC [Member] Marc Realty [Member]	Sep. 30, 2013 1701 Woodfield LLC [Member] Marc Realty [Member]	Dec. 31, 2012 1701 Woodfield LLC [Member] Marc Realty [Member]	Sep. 30, 2013 Enterprise Center LLC [Member] Marc Realty [Member]	Dec. 31, 2012 Enterprise Center LLC [Member] Marc Realty [Member]	Sep. 30, 2013 Atrium Mall LLC [Member]	Dec. 31, 2012 Atrium Mall LLC [Member]	Sep. 30, 2013 Atrium Mall LLC [Member] Marc Realty [Member]	Dec. 31, 2012 Atrium Mall LLC [Member] Marc Realty [Member]	Sep. 30, 2013 WRT - ROIC Lakeside Eagle LLC [Member]	Dec. 31, 2012 WRT - ROIC Lakeside Eagle LLC [Member]	Sep. 30, 2013 WRT - ROIC Lakeside Eagle LLC [Member] ROIC [Member]	Dec. 31, 2012 WRT - ROIC Lakeside Eagle LLC [Member] ROIC [Member]	Sep. 30, 2013 Socal Office Portfolio Loan LLC [Member]	Dec. 31, 2012 Socal Office Portfolio Loan LLC [Member]	Sep. 30, 2013 Socal Office Portfolio Loan LLC [Member] New Valley/Starwood [Member]	Dec. 31, 2012 Socal Office Portfolio Loan LLC [Member] New Valley/Starwood [Member]	Sep. 30, 2013 701 7th WRT Investors LLC [Member]	Dec. 31, 2012 701 7th WRT Investors LLC [Member]	Sep. 30, 2013 701 7th WRT Investors LLC [Member] New Valley/Witkoff [Member]	Dec. 31, 2012 701 7th WRT Investors LLC [Member] New Valley/Witkoff [Member]	Sep. 30, 2013 WRT-Fenway Wateridge LLC [Member]	Dec. 31, 2012 WRT-Fenway Wateridge LLC [Member]	Sep. 30, 2013 WRT-Fenway Wateridge LLC [Member] Fenway [Member]	Dec. 31, 2012 WRT-Fenway Wateridge LLC [Member] Fenway [Member]
Schedule Of Results Related To Equity Accounted Investees [Line Items]
Nominal % Ownership							75.00%				50.00%		50.00%	50.00%	50.00%				20.00%				33.33%	33.30%				50.00%				49.90%			17.00%		33.30%				24.80%						60.00%		68.00%		50.00%		50.00%		50.00%		50.00%		50.00%				50.00%				50.00%				73.00%				70.60%				50.00%
Equity investments	$ 139,061,000	$ 134,859,000	$ 7,741,000	$ 8,104,000	$ 33,706,000	$ 30,534,000	$ 33,706,000	$ 30,534,000		$ 460,000		$ 460,000			$ 24,518,000	$ 24,644,000	$ 8,916,000	$ 8,501,000	$ 8,916,000	$ 8,501,000	$ 11,000	$ 10,845,000		$ 11,000	$ 10,845,000	$ 993,000	$ 1,779,000	$ 993,000	$ 1,779,000	$ 596,000	$ 551,000	$ 596,000	$ 551,000										$ 982,000	$ 3,974,000	$ 4,181,000	$ 322,000	$ 7,741,000	$ 8,104,000					$ 8,076,000	$ 7,983,000	$ 2,137,000	$ 2,241,000	$ 2,052,000	$ 1,977,000	$ 2,440,000	$ 2,679,000	$ 3,904,000		$ 3,904,000		$ 3,000		$ 3,000			$ 8,000		$ 8,000	$ 36,989,000	$ 28,735,000	$ 36,989,000	$ 28,735,000	$ 1,816,000	$ 1,522,000	$ 1,816,000	$ 1,522,000
Nominal % Ownership							75.00%				50.00%		50.00%	50.00%	50.00%				20.00%				33.33%	33.30%				50.00%				49.90%			17.00%		33.30%				24.80%						60.00%		68.00%		50.00%		50.00%		50.00%		50.00%		50.00%				50.00%				50.00%				73.00%				70.60%				50.00%