Equity Investments (Details) (USD $)	Jun. 30, 2012	May 10, 2012	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		49.90%
Equity Method Investments	$ 146,221,000		$ 162,142,000
Michigan 30 LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments			10,049,000
Brooks Building LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	7,930,000		7,679,000
High Point Plaza LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	2,330,000		2,441,000
Salt Creek L L C [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage
Equity Method Investments
1701 Woodfield LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	1,979,000		2,047,000
River Road LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage
Equity Method Investments			1,000,000
3701 Algonquin Road LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage
Equity Method Investments			250,000
Enterprise Center LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	2,579,000		2,679,000
900 Ridgebrook LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage
Equity Method Investments			1,000,000
Michigan 180 Property LLC [Member] | Marc Realty [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	70.00%
Equity Method Investments	6,950,000
Northwest Atlanta Partners LP [Member] | Sealy [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	60.00%
Equity Method Investments	8,373,000		8,537,000
New Market GP LLC [Member] | Sealy [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	68.00%
Equity Method Investments	1,344,000		2,811,000
Airpark Nashville GP [Member] | Sealy [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments
Concord Debt Holdings LLC [Member] | Inland/Lexington [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.33%
Equity Method Investments	4,529,000
CDH CDO LLC [Member] | Inland/Lexington [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.33%
Equity Method Investments	2,978,000
WRT - ROIC Riverside LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	7,883,000		7,883,000
WRT - ROIC Riverside LLC [Member] | ROIC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	7,883,000		7,883,000
WRT - ROIC Lakeside Eagle LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	1,000		7,000
WRT - ROIC Lakeside Eagle LLC [Member] | ROIC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	1,000		7,000
RE CDO Management LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	1,794,000		1,296,000
RE CDO Management LLC [Member] | Atrium Holding [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	1,794,000		1,296,000
Vintage Housing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	30,144,000		29,887,000
Vintage Housing LLC [Member] | VHH LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	75.00%
Equity Method Investments	30,144,000		29,887,000
Socal Office Portfolio Loan LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	33,888,000		72,626,000
Socal Office Portfolio Loan LLC [Member] | New Valley [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.20%
Equity Method Investments	33,888,000		72,626,000
WRT-Elad One South State Equity LP [Member] | Elad Canada Ltd [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investments	24,716,000		10,150,000
WRT-Stamford LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	8,236,000
WRT-Stamford LLC [Member] | Mack-Cali [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%
Equity Method Investments	8,236,000
10 Metrotech [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	56,000
10 Metrotech [Member] | Atrium/Northstar (1) [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.30%
Equity Method Investments	56,000
Mentor Retail LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	511,000
Mentor Retail LLC [Member] | Freed [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	49.90%
Equity Method Investments	511,000
FII Co-Invest LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments			1,800,000
FII Co-Invest LLC [Member] | Broadway Partners [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage
Equity Method Investments			$ 1,800,000