Financial Instruments - Location and Pretax (Gains) or Loss Amounts for Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 42,294	$ 40,122	$ 39,807
Other (income) expense, net	(402)	(500)	189
Other comprehensive income (loss)	(361)	316	(1,078)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI on derivatives	228	(562)	210
(Decrease) increase in Sales as a result of AOCI reclassifications	160	(138)	(311)
Other (income) expense, net \| Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(27)	(48)	(29)
Derivatives designated as hedging instruments	50	12	(35)
Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest \| Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ (160)	$ 138	$ 311

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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