Real Estate Investments Real Estate Investments (Schedule of Annualized Rental Income by Major Tenants) (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Dollar General [Member]
Real Estate Properties [Line Items]
Annualized rental income, Percentage	13.40%	43.40%
FedEx [Member]
Real Estate Properties [Line Items]
Annualized rental income, Percentage	11.10%	16.20%
Walgreens [Member]
Real Estate Properties [Line Items]
Annualized rental income, Percentage		27.90%

Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

No definition available.

Name:	us-gaap_EntityWideRevenueMajorCustomerPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration