Derivatives - Cash Flow Hedges - Effective and Ineffective Portions (Details) - Cash flow hedge - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Other Comprehensive Income on Effective Portion of Derivative	$ 133	$ (311)
Pretax Gain (Loss) Recognized in Income on Effective Portion of Derivative as a Result of Reclassification from Accumulated Other Comprehensive Income	(96)	7
Foreign currency forward/option contracts
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Other Comprehensive Income on Effective Portion of Derivative	151	(305)
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	(95)	8
Interest rate swap contracts
Derivatives in Cash Flow Hedging Relationships
Pretax Gain (Loss) Recognized in Other Comprehensive Income on Effective Portion of Derivative	(18)	(6)
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)	$ (1)