Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Aug. 26, 2012	Aug. 28, 2011	Aug. 26, 2012	Aug. 28, 2011
Net periodic benefit cost (income):
Curtailment (gain) loss			$ (1,730)	$ 1,629
Changes in accumulated other comprehensive loss:
Total recognized in accumulated other comprehensive loss	(474)	2,700	(1,091)	(19,150)
Pension Benefits [Member]
Net periodic benefit cost (income):
Service cost	2,215	2,552	6,709	7,739
Interest cost	14,364	15,123	43,212	45,277
Expected return on plan assets	(12,901)	(13,535)	(39,018)	(39,490)
Amortization of prior service (benefit) cost	(20)	(20)	(61)	65
Amortization of actuarial loss	3,154	1,939	9,457	12,973
Curtailment (gain) loss	(735)	(1,426)	(1,730)	1,629
Net settlement loss	0	20	417	736
Net periodic benefit cost (income)	6,077	4,653	18,986	28,929
Changes in accumulated other comprehensive loss:
Actuarial (gain) loss	(451)	105	(381)	(32,310)
Amortization of prior service benefit (cost)	20	20	61	(65)
Amortization of actuarial loss	(3,154)	(1,939)	(9,457)	(12,973)
Curtailment gain (loss)	192	(7)	191	(3,078)
Net settlement gain (loss)	18	(9)	(178)	(347)
Total recognized in accumulated other comprehensive loss	(3,375)	(1,830)	(9,764)	(48,773)
Total recognized in net periodic benefit cost (income) and accumulated other comprehensive loss	2,702	2,823	9,222	(19,844)
Postretirement Benefits [Member]
Net periodic benefit cost (income):
Service cost	99	119	298	358
Interest cost	1,658	1,908	4,975	5,722
Expected return on plan assets	0	0	0	0
Amortization of prior service (benefit) cost	(4,089)	(7,236)	(12,267)	(21,709)
Amortization of actuarial loss	1,290	1,256	3,868	3,769
Curtailment (gain) loss	0	0	0	0
Net settlement loss	0	0	0	0
Net periodic benefit cost (income)	(1,042)	(3,953)	(3,126)	(11,860)
Changes in accumulated other comprehensive loss:
Actuarial (gain) loss	0	0	0	0
Amortization of prior service benefit (cost)	4,089	7,236	12,267	21,709
Amortization of actuarial loss	(1,290)	(1,256)	(3,868)	(3,769)
Curtailment gain (loss)	0	0	0	0
Net settlement gain (loss)	0	0	0	0
Total recognized in accumulated other comprehensive loss	2,799	5,980	8,399	17,940
Total recognized in net periodic benefit cost (income) and accumulated other comprehensive loss	$ 1,757	$ 2,027	$ 5,273	$ 6,080