Debt - CMBS - Narrative (Details)
$ in Millions
3 Months Ended
Mar. 31, 2015
USD ($)
Property
loan
Loan
Debt Instrument [Line Items]  
Number of properties securing borrowings 145
CMBS Loans | CMBS - fixed-rate  
Debt Instrument [Line Items]  
Number of loans secured by mortgage on leased properties and related assets | loan 163
Number of properties securing borrowings 505
CMBS Loans | CMBS - variable-rate  
Debt Instrument [Line Items]  
Number of loans secured by mortgage on leased properties and related assets | loan 11
Number of properties securing borrowings 123
Fixed interest rate, interest rate swaps 4.55%
CMBS Loans | Mortgages  
Debt Instrument [Line Items]  
Number of CMBS loans in default | Loan 4
Number of properties securing loans 12
Debt default amount | $ $ 77.4
Interest added to principal | $ 4.4
Lender controlled restricted cash | $ $ 14.0
Minimum | CMBS Loans | CMBS - fixed-rate  
Debt Instrument [Line Items]  
Stated interest rates 3.90%
Minimum | CMBS Loans | CMBS - variable-rate  
Debt Instrument [Line Items]  
Stated interest rates 2.67%
Minimum | CMBS Loans | Mortgages  
Debt Instrument [Line Items]  
Default interest rate 9.52%
Maximum | CMBS Loans | CMBS - fixed-rate  
Debt Instrument [Line Items]  
Stated interest rates 8.39%
Maximum | CMBS Loans | CMBS - variable-rate  
Debt Instrument [Line Items]  
Stated interest rates 3.68%
Maximum | CMBS Loans | Mortgages  
Debt Instrument [Line Items]  
Default interest rate 10.88%