Goodwill and Intangible Assets - Additional Information (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) brand	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	Jul. 16, 2019 USD ($)	Jun. 07, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense for intangible assets		$ 174,000,000	$ 176,000,000	$ 178,000,000
Estimated amortization expense for intangible assets in year 1		175,000,000
Estimated amortization expense for intangible assets in year 2		90,000,000
Estimated amortization expense for intangible assets in year 3		85,000,000
Estimated amortization expense for intangible assets in year 4		85,000,000
Estimated amortization expense for intangible assets in year 5		85,000,000
Goodwill decrease		43,000,000	0
Goodwill		20,848,000,000	20,725,000,000	21,085,000,000
Impairment of goodwill		0	0	0
Intangible asset impairment		57,000,000	68,000,000
North America
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill		9,356,000,000	9,173,000,000
Gum, Chocolate, Biscuits and Candy
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment			68,000,000
Candy and Gum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				109,000,000
Trademarks
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment		$ 57,000,000		1,000,000
Number of impaired trademarks | brand		9
Number of trademarks with fair value in excess of book value, 10% or less | brand		14
Book value of trademarks with fair value in excess of book value, 10% or less		$ 635,000,000
Trademarks | Gum, Chocolate, Biscuits and Candy | AMEA
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment		15,000,000	9,000,000
Trademarks | Gum, Chocolate, Biscuits and Candy | North America
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment			14,000,000
Trademarks | Gum, Chocolate, Biscuits and Candy | Europe
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment		39,000,000	$ 45,000,000
Trademarks | Gum, Chocolate, Biscuits and Candy | Latin America
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment		$ 3,000,000
Trademarks | Candy and Gum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				70,000,000
Trademarks | Candy and Gum | AMEA
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				52,000,000
Trademarks | Candy and Gum | North America
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				2,000,000
Trademarks | Candy and Gum | Europe
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				11,000,000
Trademarks | Candy and Gum | Latin America
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				5,000,000
Trademarks | Gum | North America
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible asset impairment				$ 38,000,000
Perfect Snacks
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill					$ 150,000,000
Intangible assets acquired					$ 138,000,000
Perfect Snacks | North America
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill						$ 150,000,000
Tate’s Bake Shop
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill adjustments	$ 1,000,000
Tate’s Bake Shop | North America
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	297,000,000						$ 298,000,000
Intangible assets acquired							$ 250,000,000
Cheese Business | AMEA
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill decrease	$ 43,000,000