Investment in Mortgage Notes Receivable (Details) (USD $)
6 Months Ended
Jun. 30, 2013
Property
Mortgage_Notes_Receivable
Dec. 31, 2012
Jun. 30, 2013
Minimum
Jun. 30, 2013
Maximum
Jun. 30, 2013
Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]          
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 $ 71,499,000 $ 73,438,000      
Mortgage notes receivable, outstanding face amount 66,500,000 68,000,000      
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 $ 3,900,000 $ 3,500,000      
Mortgage loans on real estate, interest rate     8.60% 10.47% 9.89%