Real Estate Activities Real Estate Activities - Impairment of Assets (Details) (USD $)	9 Months Ended		3 Months Ended	9 Months Ended		3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Chambersburg Mall [Member]	Sep. 30, 2011 North Hanover Mall [Member]	Sep. 30, 2013 Real Estate Investment [Member] Chambersburg Mall [Member]	Sep. 30, 2013 Real Estate Investment [Member] North Hanover Mall [Member]
Impairment of assets and expensed project costs	$ 30,416,000		$ 23,700,000	$ 24,100,000		$ 6,300,000
Real Estate, Fair Value					$ 8,200,000	$ 16,700,000