Debt - Long-term And Short-term Debt (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 28, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Debt Disclosure [Abstract]
Commercial paper and U.S. bank borrowings		$ 216		$ 829
Other bank borrowings (primarily international)		723		656
Total short-term debt		939		1,485
Debt Instrument [Line Items]
Long-term debt		13,207		13,811
Less: current portion of long-term debt		(1,017)		(1,523)
Total long-term debt		12,190		12,288
Total debt		14,146		15,296
Debt repaid		516	$ 503
1.90% Notes due 2019
Debt Instrument [Line Items]
Long-term debt		$ 0		$ 500
Debt repaid	$ 500
Interest rate	1.90%	1.90%		1.90%
Variable rate notes due 2019
Debt Instrument [Line Items]
Long-term debt		$ 150		$ 150
1.75% Euro denominated notes due 2019
Debt Instrument [Line Items]
Long-term debt		$ 560		$ 578
Interest rate		1.75%		1.75%
4.25% AUD denominated notes due 2019
Debt Instrument [Line Items]
Long-term debt		$ 71		$ 71
Interest rate		4.25%		4.25%
Variable rate notes due 2019
Debt Instrument [Line Items]
Long-term debt		$ 200		$ 200
2.25% Notes due 2020
Debt Instrument [Line Items]
Long-term debt		$ 299		$ 299
Interest rate		2.25%		2.25%
1.75% Euro denominated notes due 2020
Debt Instrument [Line Items]
Long-term debt		$ 1,154		$ 1,185
Interest rate		1.75%		1.75%
0.634% Euro denominated notes due 2020
Debt Instrument [Line Items]
Long-term debt		$ 57		$ 58
Interest rate		0.634%		0.634%
4.05% Notes due 2021
Debt Instrument [Line Items]
Long-term debt		$ 499		$ 499
Interest rate		4.05%		4.05%
3.875% Euro denominated notes due 2021
Debt Instrument [Line Items]
Long-term debt		$ 732		$ 755
Interest rate		3.875%		3.875%
3.00% Notes due 2021
Debt Instrument [Line Items]
Long-term debt		$ 498		$ 498
Interest rate		3.00%		3.00%
0.250% Euro denominated notes due 2022
Debt Instrument [Line Items]
Long-term debt		$ 1,130		$ 1,156
Interest rate		0.25%		0.25%
2.45% Notes due 2022
Debt Instrument [Line Items]
Long-term debt		$ 598		$ 598
Interest rate		2.45%		2.45%
2.20% Notes due 2022
Debt Instrument [Line Items]
Long-term debt		$ 498		$ 498
Interest rate		2.20%		2.20%
2.70% Notes due 2023
Debt Instrument [Line Items]
Long-term debt		$ 498		$ 498
Interest rate		2.70%		2.70%
2.00% Euro denominated notes due 2023
Debt Instrument [Line Items]
Long-term debt		$ 786		$ 805
Interest rate		2.00%		2.00%
5.875% GBP denominated notes due 2023
Debt Instrument [Line Items]
Long-term debt		$ 461		$ 454
Interest rate		5.875%		5.875%
1.20% Euro denominated notes due 2024
Debt Instrument [Line Items]
Long-term debt		$ 616		$ 628
Interest rate		1.20%		1.20%
1.875% Euro denominated notes due 2024
Debt Instrument [Line Items]
Long-term debt		$ 364		$ 373
Interest rate		1.875%		1.875%
2.65% Notes due 2025
Debt Instrument [Line Items]
Long-term debt		$ 398		$ 398
Interest rate		2.65%		2.65%
1.625% Euro denominated notes due 2025
Debt Instrument [Line Items]
Long-term debt		$ 556		$ 568
Interest rate		1.625%		1.625%
3.20% Notes due 2026
Debt Instrument [Line Items]
Long-term debt		$ 725		$ 725
Interest rate		3.20%		3.20%
3.434% Notes due 2026
Debt Instrument [Line Items]
Long-term debt		$ 195		$ 195
Interest rate		3.434%		3.434%
1.652% Euro denominated notes due 2027
Debt Instrument [Line Items]
Long-term debt		$ 95		$ 96
Interest rate		1.652%		1.652%
1.00% Euro denominated notes due 2028
Debt Instrument [Line Items]
Long-term debt		$ 858		$ 861
Interest rate		1.00%		1.00%
1.90% Euro denominated notes due 2030
Debt Instrument [Line Items]
Long-term debt		$ 118		$ 121
Interest rate		1.90%		1.90%
3.55% Notes due 2042
Debt Instrument [Line Items]
Long-term debt		$ 662		$ 662
Interest rate		3.55%		3.55%
Other
Debt Instrument [Line Items]
Long-term debt		$ 10		$ 10
International bank borrowings
Debt Instrument [Line Items]
Long-term debt		303		291
Obligations under capital leases
Debt Instrument [Line Items]
Long-term debt		116		81
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap
Debt Instrument [Line Items]
Fair value decrease in debt related to hedge accounting		$ 34		$ 14
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 1.75% Euro denominated notes due 2019
Debt Instrument [Line Items]
Interest rate		1.75%		1.75%
Fair value decrease in debt related to hedge accounting		$ (2)		$ (1)
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 1.75% Euro denominated notes due 2020
Debt Instrument [Line Items]
Interest rate		1.75%		1.75%
Fair value decrease in debt related to hedge accounting		$ 0		$ 0
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 3.875% Euro denominated notes due 2021
Debt Instrument [Line Items]
Interest rate		3.875%		3.875%
Fair value decrease in debt related to hedge accounting		$ 1		$ 1
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 0.250% Euro denominated notes due 2022
Debt Instrument [Line Items]
Interest rate		0.25%		0.25%
Fair value decrease in debt related to hedge accounting		$ 2		$ 2
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 2.00% Euro denominated notes due 2023
Debt Instrument [Line Items]
Interest rate		2.00%		2.00%
Fair value decrease in debt related to hedge accounting		$ 4		$ 2
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 5.875% GBP denominated notes due 2023
Debt Instrument [Line Items]
Interest rate		5.875%		5.875%
Fair value decrease in debt related to hedge accounting		$ 3		$ 1
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 1.875% Euro denominated notes due 2024
Debt Instrument [Line Items]
Interest rate		1.875%		1.875%
Fair value decrease in debt related to hedge accounting		$ 2		$ 1
Designated as Hedging Instrument | Fair Value Hedging | Interest Rate Swap | 1.00% Euro denominated notes due 2028
Debt Instrument [Line Items]
Interest rate		1.00%		1.00%
Fair value decrease in debt related to hedge accounting		$ 24		$ 8