Employee Benefit Plans - Amounts recognized in balance sheet (Details) - USD ($)	Nov. 27, 2016	Nov. 29, 2015
Pension plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	$ 5,555,000	$ 8,842,000
Accrued benefit liability – current portion	(9,142,000)	(9,044,000)
Accrued benefit liability – long-term portion	(351,025,000)	(355,612,000)
Amount recognized in balance sheet	(354,612,000)	(355,814,000)
Accumulated other comprehensive loss:
Net actuarial loss	(385,942,000)	(365,657,000)
Net prior service benefit	420,000	471,000
Other comprehensive income (loss)	(385,522,000)	(365,186,000)
Other postretirement benefit plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	0	0
Accrued benefit liability – current portion	(11,485,000)	(12,500,000)
Accrued benefit liability – long-term portion	(100,966,000)	(105,240,000)
Amount recognized in balance sheet	(112,451,000)	(117,740,000)
Accumulated other comprehensive loss:
Net actuarial loss	(28,665,000)	(26,076,000)
Net prior service benefit	0	0
Other comprehensive income (loss)	$ (28,665,000)	$ (26,076,000)