RESTRUCTURING - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 28, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Program cost to date	$ 143
Restructuring and Related Cost, Incurred Cost	$ 143
Minimum
Restructuring Cost and Reserve [Line Items]
Initial Period in which Effects are Expected to be Realized	1
Maximum
Restructuring Cost and Reserve [Line Items]
Initial Period in which Effects are Expected to be Realized	5
North America Frozen Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 70
North America Frozen Supply Chain Network Reconfiguration | Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	65
European Cereal Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	120
Restructuring and Related Cost, Incurred Cost	78
Employee related cost
Restructuring Cost and Reserve [Line Items]
Program cost to date	45
Restructuring and Related Cost, Incurred Cost	45
Employee related cost | North America Frozen Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	10
Employee related cost | European Cereal Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	50
Other cost
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	15
Other cost | North America Frozen Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	10
Other cost | European Cereal Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	30
Asset related costs
Restructuring Cost and Reserve [Line Items]
Program cost to date	23
Restructuring and Related Cost, Incurred Cost	23
Asset related costs | North America Frozen Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	50
Asset related costs | European Cereal Supply Chain Network Reconfiguration
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	40
Asset impairment
Restructuring Cost and Reserve [Line Items]
Program cost to date	60
Restructuring and Related Cost, Incurred Cost	60
Other Costs
Restructuring Cost and Reserve [Line Items]
Program cost to date	15
Restructuring and Related Cost, Incurred Cost	15
Europe
Restructuring Cost and Reserve [Line Items]
Program cost to date	78
Restructuring and Related Cost, Incurred Cost	78
North America
Restructuring Cost and Reserve [Line Items]
Program cost to date	65
Restructuring and Related Cost, Incurred Cost	$ 65