Shareholders' Equity - Components of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands  | 
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 26, 2020  | 
Sep. 28, 2019  | 
Sep. 26, 2020  | 
Sep. 28, 2019  | 
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| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||
| Other comprehensive income | $ 1,624 | $ (1,189) | $ 560 | $ (281) | 
| Foreign Currency Translation Adjustments | ||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||
| Other comprehensive income | 1,409 | (1,336) | (85) | (722) | 
| Amortization of Prior Service Cost | ||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||
| Reclassification to General and Administrative Expense | 101 | 101 | 302 | 302 | 
| Amortization of Net Actuarial Losses | ||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||
| Reclassification to General and Administrative Expense | 171 | 85 | 515 | 256 | 
| Retirement Liability Adjustment | ||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||
| Tax Benefit | (57) | (39) | (172) | (117) | 
| Other comprehensive income | $ 215 | $ 147 | $ 645 | $ 441 | 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount after tax of other comprehensive income (loss) attributable to parent entity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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