Quarterly report pursuant to Section 13 or 15(d)

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

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Accumulated Other Comprehensive Loss and Other Comprehensive Income - Components of Other Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2018
Apr. 01, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Other Comprehensive Income $ 448 $ 526
Foreign Currency Translation Adjustments    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Other Comprehensive Income 233 395
Amortization of Prior Service Cost    
Reclassifications to General and Administrative Expense:    
Reclassifications to General and Administrative Expense 101 101
Amortization of Net Actuarial Losses    
Reclassifications to General and Administrative Expense:    
Reclassifications to General and Administrative Expense 172 101
Retirement Liability Adjustment    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Other Comprehensive Income 215 131
Reclassifications to General and Administrative Expense:    
Tax Benefit $ (58) $ (71)