Pension Benefits - Schedule of Allocation of Plan Assets (Details) - Pension Plan	12 Months Ended
	Dec. 26, 2021
Pension Benefits
Percent of funded status policy maximum range	102.50%
Long Duration Assets
Pension Benefits
Target allocation percentage of assets, range minimum	85.50%
Target allocation percentage of assets, range maximum	90.50%
Public Equity
Pension Benefits
Asset allocation, actual percentage	84.00%
Growth Fixed Income
Pension Benefits
Asset allocation, actual percentage	0.00%
Alternatives
Pension Benefits
Asset allocation, actual percentage	12.00%
Cash
Pension Benefits
Asset allocation, actual percentage	4.00%
Long Duration Fixed Income
Pension Benefits
Asset allocation, actual percentage	87.00%
Long Duration and Return-Seeking Assets, Public Equity
Pension Benefits
Asset allocation, actual percentage	11.00%
Long Duration and Return-Seeking Assets, Growth Fixed Income
Pension Benefits
Asset allocation, actual percentage	0.00%
Long Duration and Return-Seeking Assets, Alternatives
Pension Benefits
Asset allocation, actual percentage	2.00%
Long Duration and Return-Seeking Assets, Cash
Pension Benefits
Asset allocation, actual percentage	0.00%
Hedging Assets
Pension Benefits
Asset allocation, actual percentage	80.00%
Return-Seeking Assets
Pension Benefits
Target allocation percentage of assets, range minimum	9.50%
Target allocation percentage of assets, range maximum	14.50%
Asset allocation, actual percentage	20.00%
Cash and Cash Equivalents
Pension Benefits
Asset allocation, actual percentage	0.00%
Minimum | Public Equity
Pension Benefits
Asset allocation, target percentage range	70.00%
Minimum | Growth Fixed Income
Pension Benefits
Asset allocation, target percentage range	0.00%
Minimum | Alternatives
Pension Benefits
Asset allocation, target percentage range	0.00%
Minimum | Cash
Pension Benefits
Asset allocation, target percentage range	0.00%
Minimum | Long Duration Fixed Income
Pension Benefits
Asset allocation, target percentage range	85.50%
Minimum | Long Duration and Return-Seeking Assets, Public Equity
Pension Benefits
Asset allocation, target percentage range	6.70%
Minimum | Long Duration and Return-Seeking Assets, Growth Fixed Income
Pension Benefits
Asset allocation, target percentage range	0.00%
Minimum | Long Duration and Return-Seeking Assets, Alternatives
Pension Benefits
Asset allocation, target percentage range	0.00%
Minimum | Long Duration and Return-Seeking Assets, Cash
Pension Benefits
Asset allocation, target percentage range	0.00%
Minimum | Hedging Assets
Pension Benefits
Asset allocation, target percentage range	75.00%
Minimum | Return-Seeking Assets
Pension Benefits
Asset allocation, target percentage range	10.00%
Minimum | Cash and Cash Equivalents
Pension Benefits
Asset allocation, target percentage range	0.00%
Maximum | Public Equity
Pension Benefits
Asset allocation, target percentage range	90.00%
Maximum | Growth Fixed Income
Pension Benefits
Asset allocation, target percentage range	15.00%
Maximum | Alternatives
Pension Benefits
Asset allocation, target percentage range	15.00%
Maximum | Cash
Pension Benefits
Asset allocation, target percentage range	10.00%
Maximum | Long Duration Fixed Income
Pension Benefits
Asset allocation, target percentage range	90.50%
Maximum | Long Duration and Return-Seeking Assets, Public Equity
Pension Benefits
Asset allocation, target percentage range	13.10%
Maximum | Long Duration and Return-Seeking Assets, Growth Fixed Income
Pension Benefits
Asset allocation, target percentage range	2.00%
Maximum | Long Duration and Return-Seeking Assets, Alternatives
Pension Benefits
Asset allocation, target percentage range	2.00%
Maximum | Long Duration and Return-Seeking Assets, Cash
Pension Benefits
Asset allocation, target percentage range	1.00%
Maximum | Hedging Assets
Pension Benefits
Asset allocation, target percentage range	90.00%
Maximum | Return-Seeking Assets
Pension Benefits
Asset allocation, target percentage range	25.00%
Maximum | Cash and Cash Equivalents
Pension Benefits
Asset allocation, target percentage range	5.00%