Long-Term Debt and Short-Term Borrowings - Long-Term Debt (Details) € in Millions, $ in Millions	Dec. 31, 2019 EUR (€)	Dec. 31, 2019 USD ($)	Aug. 31, 2019 USD ($)	Feb. 28, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Oct. 31, 2017 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2004 USD ($)
Long-Term Debt
Total long-term debt		$ 19,359			$ 14,156
Long-term debt (excluding current portion)		17,518			13,411
Floating rate medium term note due 2019
Long-Term Debt
Total long-term debt					596
Fixed rate medium term note due 2019
Long-Term Debt
Principal amount								$ 625
Total long-term debt					25
Third lien senior secured notes subject to in-substance
Long-Term Debt
Principal amount		$ 445
Interest rate - effective	12.50%	12.50%
Total long-term debt		$ 463
Floating rate Euro medium term note due 2020
Long-Term Debt
Principal amount | €	€ 650
Total long-term debt		726			743
Floating rate medium term note due 2020
Long-Term Debt
Principal amount		$ 300
Interest rate - effective	2.16%	2.16%
Total long-term debt		$ 299			294
Floating rate medium term note due 2020
Long-Term Debt
Principal amount		$ 200
Interest rate - effective	1.98%	1.98%
Total long-term debt		$ 200			197
Floating rate Eurobond due 2021
Long-Term Debt
Principal amount | €	€ 300
Total long-term debt		$ 346			357
Fixed rate Eurobond due 2021
Long-Term Debt
Principal amount | €	€ 300
Interest rate - effective	1.97%	1.97%
Total long-term debt		$ 334			341
Fixed rate medium term note due 2021
Long-Term Debt
Principal amount		$ 600
Interest rate - effective	1.63%	1.63%
Total long-term debt		$ 599			599
Fixed rate medium term note due 2021
Long-Term Debt
Principal amount		$ 200
Interest rate - effective	3.07%	3.07%
Total long-term debt		$ 199			199
Floating rate medium term notes due 2021
Long-Term Debt
Principal amount		$ 200
Interest rate - effective	1.90%	1.90%
Total long-term debt		$ 204			201
Fixed rate Euro medium term note due 2022
Long-Term Debt
Principal amount | €	€ 500
Interest rate - effective	0.45%	0.45%
Total long-term debt		$ 557			570
Fixed rate medium term note due 2022
Long-Term Debt
Principal amount		$ 600		$ 450
Interest rate - effective	2.17%	2.17%		2.75%
Total long-term debt		$ 597			596
Fixed rate medium term note due 2022
Long-Term Debt
Principal amount		$ 450
Interest rate - effective	2.76%	2.76%
Total long-term debt		$ 449
Fixed rate Euro medium term note due 2023
Long-Term Debt
Principal amount | €	€ 600
Interest rate - effective	1.14%	1.14%
Total long-term debt		$ 665			680
Fixed rate medium term notes due 2023
Long-Term Debt
Principal amount		$ 650					$ 650
Interest rate - effective	2.26%	2.26%					2.25%
Total long-term debt		$ 648			648
Fixed rate registered note due 2023
Long-Term Debt
Principal amount		$ 500	$ 500
Interest rate - effective	1.86%	1.86%	1.75%
Total long-term debt		$ 497
Floating rate medium term notes due 2024
Long-Term Debt
Principal amount		$ 300				$ 300
Interest rate - effective	2.21%	2.21%
Total long-term debt		$ 299			299
Fixed rate medium term notes due 2024
Long-Term Debt
Principal amount		$ 300				$ 300
Interest rate - effective	3.30%	3.30%				3.25%
Total long-term debt		$ 299			298
Fixed rate medium term notes due 2024
Long-Term Debt
Principal amount		$ 500		$ 500
Interest rate - effective	2.98%	2.98%		3.25%
Total long-term debt		$ 503
Fixed rate medium term note due 2025
Long-Term Debt
Principal amount		$ 550
Interest rate - effective	3.04%	3.04%
Total long-term debt		$ 547			547
Fixed rate registered note due 2025
Long-Term Debt
Principal amount		$ 750	$ 750
Interest rate - effective	2.12%	2.12%	2.00%
Total long-term debt		$ 743
Fixed rate Euro medium term note due 2026
Long-Term Debt
Principal amount | €	€ 750
Interest rate - effective	1.66%	1.66%
Total long-term debt		$ 826			844
Fixed rate medium term notes due 2026
Long-Term Debt
Principal amount		$ 650
Interest rate - effective	2.37%	2.37%
Total long-term debt		$ 643			642
Fixed rate medium term notes due 2027
Long-Term Debt
Principal amount		$ 850					$ 850
Interest rate - effective	2.95%	2.95%					2.875%
Total long-term debt		$ 842			841
Fixed rate 30-year debenture due 2028
Long-Term Debt
Principal amount		$ 220
Interest rate - effective	6.44%	6.44%
Total long-term debt		$ 226			226
Fixed rate medium term notes due 2028
Long-Term Debt
Principal amount		$ 600				$ 600
Interest rate - effective	3.62%	3.62%				3.625%
Total long-term debt		$ 597			597
Fixed rate medium term notes due 2029
Long-Term Debt
Principal amount		$ 800		$ 800
Interest rate - effective	3.38%	3.38%		3.375%
Total long-term debt		$ 796
Fixed rate registered note due 2029
Long-Term Debt
Principal amount		$ 1,000	$ 1,000
Interest rate - effective	2.50%	2.50%	2.375%
Total long-term debt		$ 984
Fixed rate Euro medium term note due 2030
Long-Term Debt
Principal amount | €	€ 500
Interest rate - effective	1.90%	1.90%
Total long-term debt		$ 549			562
Fixed rate Euro medium term notes due 2031
Long-Term Debt
Principal amount | €	€ 500
Interest rate - effective	1.54%	1.54%
Total long-term debt		$ 554			567
Fixed rate 30-year bond due 2037
Long-Term Debt
Principal amount		$ 555
Interest rate - effective	5.73%	5.73%
Total long-term debt		$ 551			551
Floating rate note due 2041
Long-Term Debt
Principal amount		$ 96
Interest rate - effective	1.58%	1.58%
Total long-term debt		$ 96			95
Fixed rate medium term note due 2044
Long-Term Debt
Principal amount		$ 325
Interest rate - effective	4.05%	4.05%
Total long-term debt		$ 314			314
Floating rate note due 2044
Long-Term Debt
Principal amount		$ 55							$ 60
Interest rate - effective	1.54%	1.54%
Total long-term debt		$ 53			53
Fixed rate medium term note due 2046
Long-Term Debt
Principal amount		$ 500
Interest rate - effective	3.37%	3.37%
Total long-term debt		$ 475			474
Fixed rate medium term note due 2047
Long-Term Debt
Principal amount		$ 500					$ 500
Interest rate - effective	3.68%	3.68%					3.625%
Total long-term debt		$ 492			491
Fixed rate medium term note due 2048
Long-Term Debt
Principal amount		$ 650				$ 650
Interest rate - effective	4.07%	4.07%				4.00%
Total long-term debt		$ 637			637
Fixed rate medium term note due 2048
Long-Term Debt
Principal amount		$ 500		$ 500
Interest rate - effective	3.78%	3.78%		4.00%
Total long-term debt		$ 506
Fixed rate registered note due 2049
Long-Term Debt
Principal amount		$ 1,000	$ 1,000
Interest rate - effective	3.37%	3.37%	3.25%
Total long-term debt		$ 968
Other borrowings
Long-Term Debt
Interest rate - effective	1.63%	1.63%
Total long-term debt		$ 76			72
The five-year credit facility and the 364-day credit facilities.
Long-Term Debt
Principal amount		$ 3,000
Current portion of long-term debt
Long-Term Debt
Interest rate - effective	3.85%	3.85%
Total long-term debt		$ 1,841			$ 745