Segment Reporting - Net Revenues by Product Category (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net revenues	$ 6,665	$ 6,355	$ 19,283	$ 18,955
Biscuits
Segment Reporting Information [Line Items]
Net revenues	3,293	2,947	9,429	8,493
Chocolate
Segment Reporting Information [Line Items]
Net revenues	2,000	1,928	5,676	5,777
Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	659	838	1,975	2,498
Beverages
Segment Reporting Information [Line Items]
Net revenues	234	217	799	835
Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	479	425	1,404	1,352
Latin America
Segment Reporting Information [Line Items]
Net revenues	610	736	1,847	2,273
Latin America | Biscuits
Segment Reporting Information [Line Items]
Net revenues	172	186	500	542
Latin America | Chocolate
Segment Reporting Information [Line Items]
Net revenues	151	164	464	551
Latin America | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	103	212	350	621
Latin America | Beverages
Segment Reporting Information [Line Items]
Net revenues	102	93	294	324
Latin America | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	82	81	239	235
AMEA
Segment Reporting Information [Line Items]
Net revenues	1,470	1,419	4,209	4,312
AMEA | Biscuits
Segment Reporting Information [Line Items]
Net revenues	550	495	1,516	1,361
AMEA | Chocolate
Segment Reporting Information [Line Items]
Net revenues	533	526	1,437	1,521
AMEA | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	173	213	511	662
AMEA | Beverages
Segment Reporting Information [Line Items]
Net revenues	109	103	437	444
AMEA | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	105	82	308	324
Europe
Segment Reporting Information [Line Items]
Net revenues	2,526	2,377	7,248	7,175
Europe | Biscuits
Segment Reporting Information [Line Items]
Net revenues	803	752	2,243	2,253
Europe | Chocolate
Segment Reporting Information [Line Items]
Net revenues	1,255	1,177	3,619	3,543
Europe | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	153	165	461	519
Europe | Beverages
Segment Reporting Information [Line Items]
Net revenues	23	21	68	67
Europe | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	292	262	857	793
North America
Segment Reporting Information [Line Items]
Net revenues	2,059	1,823	5,979	5,195
North America | Biscuits
Segment Reporting Information [Line Items]
Net revenues	1,768	1,514	5,170	4,337
North America | Chocolate
Segment Reporting Information [Line Items]
Net revenues	61	61	156	162
North America | Gum & Candy
Segment Reporting Information [Line Items]
Net revenues	230	248	653	696
North America | Beverages
Segment Reporting Information [Line Items]
Net revenues	0	0	0	0
North America | Cheese & Grocery
Segment Reporting Information [Line Items]
Net revenues	$ 0	$ 0	$ 0	$ 0