Weighted Average Assumptions Used in the Measurement of Net Periodic Benefit Cost (Detail) - North America	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.91%	4.84%	4.76%
Expected long-term rate of return on plan assets	5.85%	6.50%	6.60%
Other Benefits, United States
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.40%	4.00%	3.80%
Other Benefits, Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.00%	4.80%	4.60%