Benefits - Amounts recognized in balance sheet (Details) - USD ($) $ in Millions	Dec. 01, 2024	Nov. 26, 2023
Pension plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 107.4	$ 87.6
Accrued benefit liability – current portion(2)	(10.3)	(10.3)
Accrued benefit liability – long-term portion(2)	(110.1)	(107.3)
Amount recognized in balance sheet	(13.0)	(30.0)
Accumulated other comprehensive loss:
Net actuarial loss	(201.6)	(217.5)
Net prior service benefit	0.0	0.1
Other comprehensive income (loss)	(201.6)	(217.4)
Other postretirement benefit plans, defined benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	0.0	0.0
Accrued benefit liability – current portion(2)	(5.0)	(5.6)
Accrued benefit liability – long-term portion(2)	(30.8)	(33.6)
Amount recognized in balance sheet	(35.8)	(39.2)
Accumulated other comprehensive loss:
Net actuarial loss	0.0	0.6
Net prior service benefit	0.0	0.0
Other comprehensive income (loss)	$ 0.0	$ 0.6