Debt - Schedule of Debt Maturities (Footnote) (Details)
9 Months Ended
Sep. 30, 2017
USD ($)
extension_option
Loan
Sep. 30, 2016
USD ($)
Aug. 18, 2016
USD ($)
Debt Instrument [Line Items]      
Capitalized interest $ 2,430,000 $ 3,584,000  
CMBS fixed-rate | CMBS Loans      
Debt Instrument [Line Items]      
Debt default amount 62,900,000    
Capitalized interest 11,800,000    
Unsecured Debt      
Debt Instrument [Line Items]      
Unsecured term loan $ 420,000,000   $ 300,000,000
Number of one-year extension options | extension_option 2    
Extension option, term (in years) 1 year    
Revolving Credit Facility      
Debt Instrument [Line Items]      
Extension option, term (in years) 1 year    
Discontinued Operations, Disposed of by Sale | CMBS Loans      
Debt Instrument [Line Items]      
Number of loans in default | Loan 6