Quarterly report pursuant to Section 13 or 15(d)

Interest Rate Derivatives (Details)

v3.10.0.1
Interest Rate Derivatives (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income          
Amount of Gain (Loss) Recognized in AOCI on Derivatives $ 1,325 $ (301) $ 7,913 $ (1,877)  
Interest rate swaps | Interest Expense          
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income          
Amount of Gain (Loss) Reclassified from AOCI into Interest Expense on Statement of Operations 207 $ (615) 9 $ (2,740)  
Interest rate swaps | Interest rate derivatives          
Fair value of interest rate derivatives and balance sheet classification          
Interest rate swaps designated as cash flow hedges 10,875   10,875   $ 3,073
Designated          
Fair values of interest rate swap derivatives          
Fair value of interest rate swaps 10,875   10,875   3,073
Designated | Interest rate swaps          
Effect of interest rate derivatives on consolidated statements of operations and comprehensive income          
Approximate loss amount to be reclassified from AOCI to interest expense over the next 12 months (2,500)   (2,500)    
Designated | Interest rate swap, effective date September 1, 2015, swap two          
Fair values of interest rate swap derivatives          
Notional Amount $ 100,000   $ 100,000    
Fixed rate (as a percent) 1.73%   1.73%    
Fair value of interest rate swaps $ 695   $ 695   252
Designated | Interest rate swap, effective October 13, 2015          
Fair values of interest rate swap derivatives          
Notional Amount $ 12,931   $ 12,931    
Fixed rate (as a percent) 1.39%   1.39%    
Fair value of interest rate swaps $ 349   $ 349   213
Notional amount of interest rate derivatives after scheduled amortization 12,100   12,100    
Designated | Interest rate swap, effective September 1, 2016, swap one          
Fair values of interest rate swap derivatives          
Notional Amount $ 100,000   $ 100,000    
Fixed rate (as a percent) 1.9013%   1.9013%    
Fair value of interest rate swaps $ 3,937   $ 3,937   1,046
Designated | Interest rate swap, effective September 1, 2016, swap two          
Fair values of interest rate swap derivatives          
Notional Amount $ 100,000   $ 100,000    
Fixed rate (as a percent) 1.905%   1.905%    
Fair value of interest rate swaps $ 3,943   $ 3,943   1,051
Designated | Interest rate swap, effective September 1, 2016, swap three          
Fair values of interest rate swap derivatives          
Notional Amount $ 50,000   $ 50,000    
Fixed rate (as a percent) 1.9079%   1.9079%    
Fair value of interest rate swaps $ 1,951   $ 1,951   $ 511