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Financial Instruments - (Narratives) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 EUR (€)	Mar. 31, 2020 USD ($)	Mar. 31, 2020 GBP (£)	Dec. 31, 2019 EUR (€)	Dec. 31, 2019 USD ($)
Net Investment Hedges \| Floating Rate Notes, May 2021 Euro Notes, 2023 Euro Notes, 2027 Euro Notes, 2030 Euro Notes, 2039 Euro Notes, and ECP Notes \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Notional amount \| €			€ 8,809,000,000
Net Investment Hedges \| 3.36% Sterling Senior Notes Due May 2031 \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Notional amount \| £					£ 864,000,000
Interest rate swap \| Fair Value Hedging
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Notional amount \| €						€ 500,000,000
Interest rate swap \| Fair Value Hedging \| 1.1% Euro Senior Notes Due July 2024 \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Derivative asset fair value				$ 13			$ 10
Interest rate swap \| Net Investment Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Derivative asset fair value				$ 116
Derivative asset fair value, gross liability							$ 167
Currency forward contract \| Net Investment Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Gain (loss) for the change in fair value on derivative used in net investment hedge, after tax, recorded in other comprehensive earnings loss	$ 535	$ 7
Currency Swap \| Net Investment Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives
Notional amount			€ 2,506,000,000		£ 556,000,000