Employee Benefit Plans - Amounts recognized in balance sheet (Details) - USD ($)	Nov. 24, 2019	Nov. 25, 2018
Pension plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 27,704,000	$ 22,738,000
Accrued benefit liability – current portion	(9,480,000)	(9,390,000)
Accrued benefit liability – long-term portion	(188,825,000)	(191,491,000)
Amount recognized in balance sheet	(170,601,000)	(178,143,000)
Accumulated other comprehensive loss:
Net actuarial loss	(358,484,000)	(365,424,000)
Net prior service benefit	291,000	351,000
Other comprehensive income (loss)	(358,193,000)	(365,073,000)
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	(8,129,000)	(8,725,000)
Accrued benefit liability – long-term portion	(64,006,000)	(74,182,000)
Amount recognized in balance sheet	(72,135,000)	(82,907,000)
Accumulated other comprehensive loss:
Net actuarial loss	(11,284,000)	(14,652,000)
Net prior service benefit	0	0
Other comprehensive income (loss)	$ (11,284,000)	$ (14,652,000)