Weighted Average Assumptions Used in the Measurement of Benefit Obligations (Detail)	Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.69%	2.27%	3.26%
Other Benefits | United States
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.40%	1.90%	2.80%
Other Benefits | Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.90%	2.50%	3.10%