Accumulated Other Comprehensive Income (Loss) - Income (Expense) Effect of Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Affected Line Item on the Statements of Income [Line Items]
Other Income (Expense) - net	$ (112)	$ 174	$ (159)	$ 235
Interest Expense	(222)	(224)	(439)	(448)
Income Taxes	(76)	(192)	(205)	(371)
Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Total After-tax	(58)	(117)	(89)	(70)
Qualifying Derivatives [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	(32)	(106)	(31)	(9)
Income Taxes	7	21	7	2
Total After-tax	(25)	(85)	(24)	(7)
Qualifying Derivatives [Member] | Interest Rate Swaps [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Interest Expense	(2)	(2)	(5)	(3)
Qualifying Derivatives [Member] | Cross Currency Swaps [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Other Income (Expense) - net	(29)	(103)	(26)	(6)
Interest Expense	(1)	(1)	0	0
Equity Investees Accumulated Other Comprehensive Income [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Other Income (Expense) - net	(1)	1	(1)	1
Total Pre-tax	(1)	1	(1)	1
Income Taxes	0	0	0	0
Total After-tax	(1)	1	(1)	1
Defined Benefit Plans [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	(41)	(41)	(82)	(81)
Income Taxes	9	8	18	17
Total After-tax	(32)	(33)	(64)	(64)
Defined Benefit Plans [Member] | Prior Service Costs [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	(1)	(1)	(1)	(1)
Defined Benefit Plans [Member] | Net Actuarial Loss [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Total Pre-tax	$ (40)	$ (40)	$ (81)	$ (80)