Investment in Mortgage Notes Receivable (Details) (USD $)
6 Months Ended
Jun. 30, 2012
Property
Mortgage_Notes_Receivable
Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Document Period End Date Jun. 30, 2012  
Number of mortgage notes receivable (in number of mortgage notes receivable) 69  
Number of restaurant properties securing mortgage notes receivable (in properties) 43  
Number of single-tenant retail properties securing mortgage notes receivable (in properties) 26  
Investment in mortgage notes receivable, net $ 75,139,000 $ 76,745,000
Mortgage notes receivable, outstanding face amount 69,300,000 70,600,000
Mortgage notes receivable, premium 6,900,000 6,900,000
Mortgage notes receivable, acquisition costs 2,000,000 2,000,000
Mortgage notes receivable, accumulated amortization of premium and amortization of acquisition costs $ 3,100,000 $ 2,800,000
Minimum
   
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Mortgage loans on real estate, interest rate 8.60%  
Maximum
   
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Mortgage loans on real estate, interest rate 10.47%  
Weighted Average
   
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Mortgage loans on real estate, interest rate 9.89%