Shareholders' Equity (AOCI and Reclassification) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 25, 2020	Dec. 27, 2019
AOCI Attributable to Parent, Net of Tax
Beginning Balance	$ (124,165)	$ (169,787)	$ (144,857)
Other comprehensive income (loss) before reclassifications	24,927	38,178	(32,036)
Amounts reclassified from accumulated other comprehensive income	19,069	7,444	7,106
Ending Balance	(80,169)	(124,165)	(169,787)
Pension and Postretirement Medical
AOCI Attributable to Parent, Net of Tax
Beginning Balance	(114,129)	(113,721)	(86,889)
Other comprehensive income (loss) before reclassifications	34,953	(7,852)	(33,938)
Amounts reclassified from accumulated other comprehensive income	19,069	7,444	7,106
Ending Balance	(60,107)	(114,129)	(113,721)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax
Beginning Balance	(10,036)	(56,066)	(57,968)
Other comprehensive income (loss) before reclassifications	(10,026)	46,030	1,902
Amounts reclassified from accumulated other comprehensive income	0	0	0
Ending Balance	$ (20,062)	$ (10,036)	$ (56,066)

- Definition

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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