Debt - CMBS - Narrative (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Property
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 163
Effective percentage rate minimum 3.90%
Effective percentage rate maximum 8.39%
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 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 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 - variable-rate  
Debt Instrument [Line Items]  
Weighted Average Stated Rates 2.67%
Minimum | CMBS Loans | Mortgages  
Debt Instrument [Line Items]  
Default interest rate 9.52%
Maximum | CMBS Loans | CMBS - variable-rate  
Debt Instrument [Line Items]  
Weighted Average Stated Rates 3.68%
Maximum | CMBS Loans | Mortgages  
Debt Instrument [Line Items]  
Default interest rate 10.88%