Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Derivative Financial Instruments (Details)

v3.8.0.1
Summary of Significant Accounting Policies - Derivative Financial Instruments (Details) - Interest rate swap instruments
$ in Thousands
 1 Months Ended
Jun. 30, 2017
Sep. 30, 2015
USD ($)
Oct. 31, 2012
USD ($)
swap
Jul. 31, 2011
USD ($)
Mar. 31, 2010
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2013
USD ($)
Dec. 31, 2007
USD ($)
contract
Derivative [Line Items]                
Number of instruments held | contract               2
Interest Rate Swap Contract 1                
Derivative [Line Items]                
Initial notional amount of interest rate swaps               $ 13,081
Interest rate swaps, variable to fixed interest rates               5.40%
Interest Rate Swap Contract 2                
Derivative [Line Items]                
Initial notional amount of interest rate swaps               $ 3,256
Interest rate swaps, variable to fixed interest rates               5.30%
Interest Rate Swap Contract 3                
Derivative [Line Items]                
Initial notional amount of interest rate swaps         $ 27,900      
Interest rate swaps, variable to fixed interest rates         3.74%      
Term of interest rate swap contract         14 years      
Interest Rate Swap Contract 4                
Derivative [Line Items]                
Initial notional amount of interest rate swaps       $ 38,571        
Interest rate swaps, variable to fixed interest rates       1.965%        
Term of interest rate swap contract       5 years        
Interest Rate Swap Contract 5                
Derivative [Line Items]                
Number of instruments held | swap     2          
Initial notional amount of interest rate swaps     $ 16,750          
Interest rate swaps, variable to fixed interest rates     1.71%          
Term of interest rate swap contract     8 years          
Future increase in notional amount             $ 42,247  
Interest Rate Swap Contract 6                
Derivative [Line Items]                
Number of instruments held | swap     2          
Initial notional amount of interest rate swaps     $ 25,377          
Interest rate swaps, variable to fixed interest rates     3.70%          
Term of interest rate swap contract     8 years          
Interest Rate Swap Contract 7                
Derivative [Line Items]                
Initial notional amount of interest rate swaps   $ 20,746            
Interest rate swaps, variable to fixed interest rates   2.19%            
Term of interest rate swap contract   7 years            
Interest Rate Swap Contract 8                
Derivative [Line Items]                
Initial notional amount of interest rate swaps   $ 14,084            
Interest rate swaps, variable to fixed interest rates   3.26%            
Term of interest rate swap contract   15 years            
Interest Rate Swap Contract 9                
Derivative [Line Items]                
Initial notional amount of interest rate swaps           $ 14,100    
Interest rate swaps, variable to fixed interest rates           2.29%    
Term of interest rate swap contract 10 years