Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Liabilities and Assets Measured at Fair Value (Details)

v3.8.0.1
Fair Value Measurements - Liabilities and Assets Measured at Fair Value (Details) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Other assets | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-COLI assets held in Deferred Supplemental Compensation Plan $ 389 $ 299
Other current assets | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Interest rate swaps $ 294 $ 73