Quarterly report pursuant to Section 13 or 15(d)

Debt, Net (Details)

v3.8.0.1
Debt, Net (Details)
3 Months Ended
Mar. 31, 2018
USD ($)
extension
Mar. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
Debt      
Carrying Value $ 1,854,886,000   $ 1,828,333,000
Interest costs capitalized 1,400,000 $ 1,500,000  
Secured Debt      
Debt      
Carrying Value $ 162,864,000   163,838,000
Line of Credit | Revolving Credit Facility      
Debt      
Number of extensions | extension 2    
Extension option period (in years) 6 months    
Line of credit facility, extension fee percentage 0.075%    
Loans payable      
Debt      
Deferred financing costs, net $ 4,800,000   5,000,000
Fixed rate debt | Secured Debt      
Debt      
Carrying Value 149,835,000   150,723,000
Unamortized premium included in carrying value $ 332,000   349,000
Weighted average interest rate (as a percent) 4.18%    
Fixed rate debt | Secured Debt | Minimum      
Debt      
Stated interest rate (as a percent) 3.82%    
Fixed rate debt | Secured Debt | Maximum      
Debt      
Stated interest rate (as a percent) 7.87%    
Variable-rate debt | Secured Debt      
Debt      
Carrying Value $ 13,029,000   13,115,000
Stated interest rate (as a percent) 3.51%    
Variable-rate debt | Secured Debt | London Interbank Offered Rate (LIBOR)      
Debt      
Variable rate, spread (as a percent) 1.85%    
Revolving Credit Facility      
Debt      
Carrying Value $ 153,000,000   126,000,000
Weighted average interest rate (as a percent) 2.77%    
Revolving Credit Facility | Minimum | London Interbank Offered Rate (LIBOR)      
Debt      
Variable rate, spread (as a percent) 0.875%    
Revolving Credit Facility | Maximum | London Interbank Offered Rate (LIBOR)      
Debt      
Variable rate, spread (as a percent) 1.60%    
Term Loan Facilities      
Debt      
Carrying Value $ 348,072,000   347,959,000
Weighted average interest rate (as a percent) 3.03%    
Aggregate additional borrowing capacity available $ 350,000,000    
Term Loan Facilities | Minimum | London Interbank Offered Rate (LIBOR)      
Debt      
Variable rate, spread (as a percent) 0.90%    
Term Loan Facilities | Maximum | London Interbank Offered Rate (LIBOR)      
Debt      
Variable rate, spread (as a percent) 1.85%    
3.60% Senior Notes | Unsecured senior notes      
Debt      
Carrying Value $ 347,659,000   347,551,000
Debt instrument, face amount $ 350,000,000    
Stated interest rate (as a percent) 3.60%    
Unamortized discount included in carrying value $ 1,600,000   1,700,000
Interest rate on debt (as a percent) 3.70%    
5.250% Senior Notes | Unsecured senior notes      
Debt      
Carrying Value $ 246,765,000   246,645,000
Debt instrument, face amount $ 250,000,000    
Stated interest rate (as a percent) 5.25%    
Unamortized discount included in carrying value $ 2,900,000   3,000,000
Interest rate on debt (as a percent) 5.49%    
3.70% Senior Notes | Unsecured senior notes      
Debt      
Carrying Value $ 298,444,000   298,322,000
Debt instrument, face amount $ 300,000,000    
Stated interest rate (as a percent) 3.70%    
Unamortized discount included in carrying value $ 1,200,000   1,300,000
Interest rate on debt (as a percent) 3.85%    
5.000% Senior Notes | Unsecured senior notes      
Debt      
Carrying Value $ 296,824,000   296,731,000
Debt instrument, face amount $ 300,000,000    
Stated interest rate (as a percent) 5.00%    
Unamortized discount included in carrying value $ 2,600,000   2,700,000
Interest rate on debt (as a percent) 5.15%    
Unsecured notes payable      
Debt      
Carrying Value $ 1,258,000   1,287,000
Stated interest rate (as a percent) 0.00%    
Unamortized discount included in carrying value $ 353,000   $ 373,000