Accumulated Other Comprehensive Income (Loss) (Income (Expense) Effect of Reclassifications) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Affected Line Item on the Statements of Income
Interest Expense	$ (901)	$ (888)	$ (871)
Other Income (Expense) - net	(255)	390	108
Total Pre-tax	1,912	2,550	2,068
Income Taxes	(784)	(648)	(465)
Total After-Tax	1,128	1,902	1,603
Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total After-Tax	(205)	(30)	(145)
Available For Sale Securities [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Other Income (Expense) - net	0	0	4
Total Pre-tax	0	0	4
Income Taxes	0	0	(2)
Total After-Tax	0	0	2
Qualifying Derivatives [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total Pre-tax	(91)	112	(17)
Income Taxes	18	(21)	15
Total After-Tax	(73)	91	(2)
Qualifying Derivatives [Member] | Interest Rate Swaps [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Interest Expense	(9)	(7)	(11)
Discontinued operations	0	0	(77)
Qualifying Derivatives [Member] | Cross Currency Swaps [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Interest Expense	0	3	2
Other Income (Expense) - net	(82)	116	49
Qualifying Derivatives [Member] | Commodity Contracts [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Discontinued operations	0	0	20
Equity Investees AOCI [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Other Income (Expense) - net	(1)	1	1
Total Pre-tax	(1)	1	1
Income Taxes	0	0	0
Total After-Tax	(1)	1	1
Defined Benefit Plans [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total Pre-tax	(169)	(158)	(192)
Income Taxes	38	36	46
Total After-Tax	(131)	(122)	(146)
Defined Benefit Plans [Member] | Prior Service Costs [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total Pre-tax	(2)	(2)	0
Defined Benefit Plans [Member] | Net Actuarial Loss [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total Pre-tax	$ (167)	$ (156)	$ (192)