Debt - Debt Maturities - Narrative (Details) (USD $)
Sep. 30, 2014
Dec. 31, 2013
Debt Instrument [Line Items]    
Deferred finance costs $ 39,700,000 $ 23,800,000
Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Balloon payments 2,094,641,000  
Accelerated Principal | Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Debt default amount 74,000,000 [1]  
2019 | Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Balloon payments 452,000,000  
2020 | Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Balloon payments 288,000,000  
2021 | Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Balloon payments 554,800,000  
2022 | Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Balloon payments 351,400,000  
2023 | Mortgages and Notes Payable
   
Debt Instrument [Line Items]    
Balloon payments $ 352,100,000  
[1] The balloon payment balance in 2014 includes $74.0 million for the acceleration of principal payable following an event of default under four separate CMBS loans.