Derivatives - Cash Flow Hedges - Effective and Ineffective Portions (Details) - Cash flow hedge - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Other Comprehensive Income on Effective Portion of Derivative	$ 22	$ 122
Pretax Gain (Loss) Recognized in Income on Effective Portion of Derivative as a Result of Reclassification from Accumulated Other Comprehensive Income	(37)	(99)
Foreign currency forward/option contracts
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Other Comprehensive Income on Effective Portion of Derivative	12	112
Foreign currency forward/option contracts | Cost of sales
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Income on Effective Portion of Derivative as a Result of Reclassification from Accumulated Other Comprehensive Income	(37)	(98)
Interest rate swap contracts
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Other Comprehensive Income on Effective Portion of Derivative	$ 10	10
Interest rate swap contracts | Interest expense.
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Income on Effective Portion of Derivative as a Result of Reclassification from Accumulated Other Comprehensive Income		$ (1)