Weighted Average Assumptions Used in the Measurement of Benefit Obligations (Detail)	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Pension Benefits
Weighted Average Discount Rate [Line Items]
Discount rate	4.31%	3.71%	4.11%
Other Benefits | United States
Weighted Average Discount Rate [Line Items]
Discount rate	3.90%	3.30%	3.60%
Other Benefits | Canada
Weighted Average Discount Rate [Line Items]
Discount rate	3.90%	3.40%	3.80%