Debt - Revolving Credit Facilities - Narrative (Details) - USD ($)
 3 Months Ended 9 Months Ended
Mar. 31, 2015
Jun. 30, 2016
Sep. 30, 2016
Apr. 27, 2016
Apr. 26, 2016
Mar. 27, 2016
Dec. 31, 2015
Line of Credit Facility [Line Items]              
Unamortized deferred financing costs     $ 38,812,000       $ 41,577,000
Amount outstanding     $ 105,000,000       0
Unsecured Debt              
Line of Credit Facility [Line Items]              
Line of credit facility, maximum borrowing capacity $ 600,000,000.0     $ 800,000,000 $ 600,000,000    
Line of credit facility, accordion feature, increase limit $ 1,000,000,000.0            
Commitment fee percentage     0.25%        
Origination costs       4,800,000      
Amount outstanding     $ 105,000,000        
Letters of credit issued     300,000        
Line of credit facility remaining borrowing capacity     $ 694,700,000        
Unsecured Debt | Minimum              
Line of Credit Facility [Line Items]              
Commitment fee percentage   0.125%          
Unsecured Debt | Maximum              
Line of Credit Facility [Line Items]              
Commitment fee percentage   0.30%          
Unsecured Debt | LIBOR              
Line of Credit Facility [Line Items]              
Basis spread on variable rate     1.25%        
Unsecured Debt | LIBOR | Minimum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate   0.875%          
Unsecured Debt | LIBOR | Maximum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate   1.55%          
Unsecured Debt | Base Rate | Minimum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate   0.00%          
Unsecured Debt | Base Rate | Maximum              
Line of Credit Facility [Line Items]              
Basis spread on variable rate   0.55%          
Unsecured Debt | Swing-line Loans              
Line of Credit Facility [Line Items]              
Line of credit facility, maximum borrowing capacity       50,000,000.0      
Unsecured Debt | Letters of Credit              
Line of Credit Facility [Line Items]              
Line of credit facility, maximum borrowing capacity       $ 60,000,000.0      
Credit Facility              
Line of Credit Facility [Line Items]              
Commitment fee on unused capacity 0.35%            
Debt extinguishment costs $ 2,000,000            
Credit Facility | LIBOR              
Line of Credit Facility [Line Items]              
Basis spread on variable rate 2.50%            
Secured Debt              
Line of Credit Facility [Line Items]              
Line of credit facility, maximum borrowing capacity $ 400,000,000.0            
Revolving Line of Credit | Special Purpose Entity              
Line of Credit Facility [Line Items]              
Line of credit facility, maximum borrowing capacity           $ 40,000,000.0  
Deferred Costs And Other Assets | Revolving Line of Credit              
Line of Credit Facility [Line Items]              
Unamortized deferred financing costs     $ 3,200,000       $ 3,200,000