Employee Benefit Plans - Amounts recognized in balance sheet (Details) - USD ($)	Nov. 25, 2018	Nov. 26, 2017
Pension plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 22,738,000	$ 24,644,000
Accrued benefit liability – current portion	(9,390,000)	(9,316,000)
Accrued benefit liability – long-term portion	(191,491,000)	(310,474,000)
Amount recognized in balance sheet	(178,143,000)	(295,146,000)
Accumulated other comprehensive loss:
Net actuarial loss	(365,424,000)	(362,602,000)
Net prior service benefit	351,000	419,000
Other comprehensive income (loss)	(365,073,000)	(362,183,000)
Other postretirement benefit plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	0	0
Accrued benefit liability – current portion	(8,725,000)	(9,427,000)
Accrued benefit liability – long-term portion	(74,182,000)	(89,248,000)
Amount recognized in balance sheet	(82,907,000)	(98,675,000)
Accumulated other comprehensive loss:
Net actuarial loss	(14,652,000)	(21,878,000)
Net prior service benefit	0	0
Other comprehensive income (loss)	$ (14,652,000)	$ (21,878,000)