Real Estate Activities Real Estate Activities - Impairment of Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of Asset Impairments [Line Items]
Asset Impairment Charges	$ 14,118	$ 28,667	$ 14,724	$ 34,907
Impairment of assets and expensed project costs			14,964	$ 35,145
Washington Crown Center [Member]
Schedule of Asset Impairments [Line Items]
Impairment of assets and expensed project costs			14,100
Voorhees Town Center [Member]
Schedule of Asset Impairments [Line Items]
Impairment of assets and expensed project costs			$ 600