Accumulated Other Comprehensive Income (Loss) (Income (Expense) Effect of Reclassifications) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	[1]	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Affected Line Item on the Statements of Income
Interest Expense									$ (888)	$ (871)	$ (843)
Other Income (Expense) - net									390	108	105
Total Pre-tax									2,550	2,068	2,129
Income Taxes									(648)	(465)	(692)
Total After-Tax	$ 405		$ 396		$ 250		$ 552		1,902	1,603	$ 1,437
Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total After-Tax									(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	4
Total Pre-tax									0	4
Income Taxes									0	(2)
Total After-Tax									0	2
Qualifying Derivatives [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Total Pre-tax									112	(17)
Income Taxes									(21)	15
Total After-Tax									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									(7)	(11)
Discontinued operations									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									3	2
Other Income (Expense) - net									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	20
Equity Investees Accumulated Other Comprehensive Income [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income
Other Income (Expense) - net									1	1
Total Pre-tax									1	1
Income Taxes									0	0
Total After-Tax									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									(158)	(192)
Income Taxes									36	46
Total After-Tax									(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)	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									$ (156)	$ (192)

[1] Quarterly results can vary depending on, among other things, weather. Accordingly, comparisons among quarters of a year may not be indicative of overall trends and changes in operations.