Employee Benefit Plans - Amounts recognized in balance sheet (Details) - USD ($)	Nov. 26, 2017	Nov. 27, 2016
Pension plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 24,644,000	$ 5,555,000
Accrued benefit liability – current portion	(9,316,000)	(9,142,000)
Accrued benefit liability – long-term portion	(310,474,000)	(351,025,000)
Amount recognized in balance sheet	(295,146,000)	(354,612,000)
Accumulated other comprehensive loss:
Net actuarial loss	(362,602,000)	(385,942,000)
Net prior service benefit	419,000	420,000
Other comprehensive income (loss)	(362,183,000)	(385,522,000)
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	(9,427,000)	(11,485,000)
Accrued benefit liability – long-term portion	(89,248,000)	(100,966,000)
Amount recognized in balance sheet	(98,675,000)	(112,451,000)
Accumulated other comprehensive loss:
Net actuarial loss	(21,878,000)	(28,665,000)
Net prior service benefit	0	0
Other comprehensive income (loss)	$ (21,878,000)	$ (28,665,000)