Other Postretirement Benefits - Other Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Dec. 25, 2011	Dec. 26, 2010	Mar. 28, 2010	Dec. 26, 2010
Other Postretirement Benefits
Postemployment benefits liability	$ 20,300	$ 20,200		$ 20,200
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect	20,000
Tax charge for reduction in future tax benefits for certain retiree health benefits		$ 500	$ 10,900	$ 11,400