Weighted Average Assumptions Used to Determine Benefit Costs and Benefit Obligations (Detail)	12 Months Ended
	Dec. 28, 2012	Dec. 30, 2011	Dec. 31, 2010
Employee Benefit Plans [Line Items]
Discount rate used to determine benefit costs	5.00%	5.75%	6.00%
Discount rate used to determine benefit obligation	4.50%	5.00%	5.75%
Expected long-term rate of return on assets	6.50%	6.50%	6.50%