Divestitures and Acquisitions (Details) - USD ($) $ in Millions		3 Months Ended				4 Months Ended	9 Months Ended		12 Months Ended
	Jul. 16, 2019	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Jun. 07, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Payment to acquire business, net of cash received							$ 284	$ 528
Goodwill		$ 20,465				$ 20,465	20,465			$ 20,725
Divestiture transaction costs		3		$ 0			44	$ 0
North America
Business Acquisition [Line Items]
Goodwill		9,341				9,341	9,341			9,173
AMEA
Business Acquisition [Line Items]
Goodwill		3,098				3,098	3,098			$ 3,210
AMEA | Cheese Business | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Proceeds from divestiture of businesses						161
Current assets divested		19				19	19
Non-current assets divested		96				96	96
Divestiture transaction costs						2
Gain on divestiture, net of transaction costs						44
Perfect Snacks
Business Acquisition [Line Items]
Goodwill		150				$ 150	150
Perfect Snacks | North America
Business Acquisition [Line Items]
Payment to acquire business, net of cash received	$ 284
Definite-lived intangibles assets acquired	31
Indefinite-lived intangibles assets acquired	107
Goodwill	150
Property, plant, and equipment acquired	1
Inventory acquired	12
Accounts receivable acquired	8
Current liabilities assumed	13
Deferred tax liabilities assumed	3
Other liabilities assumed	$ 9
Incremental revenues from acquisition		$ 26					$ 26
Tate’s Bake Shop | North America
Business Acquisition [Line Items]
Payment to acquire business, net of cash received			$ 527		$ 528
Definite-lived intangibles assets acquired			45
Indefinite-lived intangibles assets acquired			205
Goodwill			297
Property, plant, and equipment acquired			16
Inventory acquired			5
Accounts receivable acquired			9
Current liabilities assumed			7
Deferred tax liabilities assumed			$ 43
Incremental revenues from acquisition									$ 35