Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Activities - Fair Value of Derivative Instruments on the Balance Sheet (Details)

v3.8.0.1
Derivative Instruments and Hedging Activities - Fair Value of Derivative Instruments on the Balance Sheet (Details) - Interest rate swap contracts
$ in Thousands
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Feb. 28, 2013
swap
Dec. 31, 2007
swap
Derivatives, Fair Value [Line Items]        
Number of instruments | swap       2
Designated as Hedging Instrument | Other assets        
Derivatives, Fair Value [Line Items]        
Asset derivatives | $ $ 233 $ 0    
Designated as Hedging Instrument | Other liabilities        
Derivatives, Fair Value [Line Items]        
Liability derivatives | $ $ 3,529 $ 3,843    
Not Designated as Hedging Instrument        
Derivatives, Fair Value [Line Items]        
Number of instruments | swap     1