Quarterly report pursuant to Section 13 or 15(d)

Accumulated Other Comprehensive Loss and Other Comprehensive Income - Components of Accumulated Other Comprehensive Loss (Details)

v3.10.0.1
Accumulated Other Comprehensive Loss and Other Comprehensive Income - Components of Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Mar. 31, 2018
Sep. 29, 2018
Sep. 30, 2017
Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Total Shareholders’ Equity   $ 369,445   $ 329,927
Adoption of ASU 2018-02 $ 1,400      
Foreign Currency Translation Adjustments        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Total Shareholders’ Equity   (5,811)   (4,465)
Retirement Liability Adjustment        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Total Shareholders’ Equity   (9,614)   (8,887)
Retirement Liability Adjustment – Before Tax   (12,170)   (12,988)
Tax Benefit of Retirement Liability Adjustment   3,929   4,101
Adoption of ASU 2018-02   (1,373) $ 0  
Accumulated Other Comprehensive Loss        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Total Shareholders’ Equity   (15,425)   $ (13,352)
Adoption of ASU 2018-02   $ (1,373)