Shareholders' Equity - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Accumulated other comprehensive income (loss)	$ (163,682)	$ (139,312)	$ (169,787)	$ (144,857)
Other comprehensive income (loss) before reclassifications	30,966	(6,396)	33,045	(3,995)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,801	1,763	5,827	4,907
Ending Accumulated other comprehensive income (loss)	(130,915)	(143,945)	(130,915)	(143,945)
Foreign Currency Transaction Loss, before Tax			24,000
Restructuring Reserve, Current	24,000		24,000
Pension and Postretirement Medical
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Accumulated other comprehensive income (loss)	(109,695)	(83,745)	(113,721)	(86,889)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,801	1,763	5,827	4,907
Ending Accumulated other comprehensive income (loss)	(107,894)	(81,982)	(107,894)	(81,982)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Accumulated other comprehensive income (loss)	(53,987)	(55,567)	(56,066)	(57,968)
Other comprehensive income (loss) before reclassifications	30,966	(6,396)	33,045	(3,995)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0	0
Ending Accumulated other comprehensive income (loss)	$ (23,021)	$ (61,963)	$ (23,021)	$ (61,963)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount before tax of foreign currency transaction realized and unrealized loss recognized in the income statement.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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