Other Postretirement Benefits - Other Information (Details) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended
	Oct. 31, 2011	Dec. 26, 2010	Dec. 30, 2012	Dec. 25, 2011	Jan. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 30, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 25, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 26, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]
Other Postretirement Benefits
Effect of curtailment					$ 27,200,000	$ 27,213,000	$ 0	$ 0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect	20,000,000
Tax charge for reduction in future tax benefits for certain retiree health benefits		11,400,000
Postemployment benefits liability			$ 19,900,000	$ 20,300,000