Segment Reporting - Net Revenues by Product Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Net revenues	$ 6,707	$ 6,538
Biscuits
Segment Reporting Information [Line Items]
Net revenues	3,026	2,737
Chocolate
Segment Reporting Information [Line Items]
Net revenues	2,156	2,206
Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	781	813
Beverages
Segment Reporting Information [Line Items]
Net revenues	298	321
Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	446	461
Latin America
Segment Reporting Information [Line Items]
Net revenues	726	800
Latin America | Biscuits
Segment Reporting Information [Line Items]
Net revenues	174	170
Latin America | Chocolate
Segment Reporting Information [Line Items]
Net revenues	194	230
Latin America | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	182	200
Latin America | Beverages
Segment Reporting Information [Line Items]
Net revenues	102	123
Latin America | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	74	77
AMEA
Segment Reporting Information [Line Items]
Net revenues	1,502	1,541
AMEA | Biscuits
Segment Reporting Information [Line Items]
Net revenues	508	461
AMEA | Chocolate
Segment Reporting Information [Line Items]
Net revenues	543	557
AMEA | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	185	225
AMEA | Beverages
Segment Reporting Information [Line Items]
Net revenues	171	172
AMEA | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	95	126
Europe
Segment Reporting Information [Line Items]
Net revenues	2,584	2,551
Europe | Biscuits
Segment Reporting Information [Line Items]
Net revenues	746	734
Europe | Chocolate
Segment Reporting Information [Line Items]
Net revenues	1,363	1,360
Europe | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	173	173
Europe | Beverages
Segment Reporting Information [Line Items]
Net revenues	25	26
Europe | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	277	258
North America
Segment Reporting Information [Line Items]
Net revenues	1,895	1,646
North America | Biscuits
Segment Reporting Information [Line Items]
Net revenues	1,598	1,372
North America | Chocolate
Segment Reporting Information [Line Items]
Net revenues	56	59
North America | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	241	215
North America | Beverages
Segment Reporting Information [Line Items]
Net revenues	0	0
North America | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	$ 0	$ 0