Real Estate Investments (Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
MICHIGAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity Wide Revenue, Major State, Percentage	15.20%	23.40%
SOUTH CAROLINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity Wide Revenue, Major State, Percentage	10.60%	23.40%
IOWA
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity Wide Revenue, Major State, Percentage	10.00%
OHIO
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity Wide Revenue, Major State, Percentage	10.80%	16.80%