Pension and Other Postretirement Plans (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 01, 2012	Aug. 27, 2011	Sep. 01, 2012	Aug. 27, 2011
Defined Benefit Plan Disclosure [Line Items]
Cash contributions	$ 5,394		$ 20,372
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions	5,369	10,510	20,297	12,752
Components of net periodic benefit cost (income):
Service cost	529	492	1,589	1,476
Interest cost	1,978	2,013	5,937	6,037
Expected return on plan assets	(2,103)	(1,923)	(6,311)	(5,766)
Settlement cost	0	0	0	1,368
Amortization of unrecognized:
Prior service cost	(2)	(98)	(8)	(296)
Net actuarial loss (gain)	1,909	1,265	5,727	3,688
Net periodic benefit cost (income)	2,311	1,749	6,934	6,507
Postretirement Healthcare Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash contributions	25	30	75	90
Components of net periodic benefit cost (income):
Interest cost	4	6	12	18
Amortization of unrecognized:
Prior service cost	(31)	(31)	(93)	(93)
Net actuarial loss (gain)	(30)	(32)	(90)	(96)
Net periodic benefit cost (income)	$ (57)	$ (57)	$ (171)	$ (171)