Accumulated Other Comprehensive Income (Loss) - Income (Expense) Effect of Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Affected Line Item on the Statements of Income [Line Items]
Interest Expense	$ (183)	$ (161)	$ (810)	$ (479)
Other Income (Expense) - net	12	6	25	11
Income Tax Expense (Benefit)	(51)	(165)	(455)	(266)
Income (Loss) from Discontinued Operations (net of income taxes)	(2)	164	(1,490)	705
Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Total After-tax	(20)	(100)	(3,722)	(173)
Amounts Reclassified From Accumulated Other Comprehensive Income [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Affected Line Item on the Statements of Income [Line Items]
Income Tax Expense (Benefit)	0	0	(660)	0
Income (Loss) from Discontinued Operations (net of income taxes)	0	0	(3,578)	0
Income before income taxes	0	0	(4,238)	0
Defined Benefit Plans [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Income (Loss) from Continuing Operations before Income Taxes	(26)	(65)	(150)	(184)
Income Tax Expense (Benefit)	7	13	31	36
Total After-tax	(19)	(52)	(119)	(148)
Defined Benefit Plans [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Affected Line Item on the Statements of Income [Line Items]
Income before income taxes	0	0	(3,577)	0
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]
Income (Loss) from Continuing Operations before Income Taxes	(12)	(1)	(3)	(3)
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]
Income (Loss) from Continuing Operations before Income Taxes	(14)	(64)	(147)	(181)
Foreign currency translation adjustments [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Affected Line Item on the Statements of Income [Line Items]
Income before income taxes	0	0	(646)	0
Unrealized gains (losses) on qualifying derivatives [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Affected Line Item on the Statements of Income [Line Items]
Income (Loss) from Continuing Operations before Income Taxes	(1)	(60)	(29)	(33)
Income Tax Expense (Benefit)	0	12	4	8
Total After-tax	(1)	(48)	(25)	(25)
Unrealized gains (losses) on qualifying derivatives [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Affected Line Item on the Statements of Income [Line Items]
Income before income taxes	0	0	(15)	0
Unrealized gains (losses) on 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	(1)	(3)	12	(7)
Income (Loss) from Discontinued Operations (net of income taxes)	0	(1)	(2)	(2)
Unrealized gains (losses) on 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]
Income (Loss) from Discontinued Operations (net of income taxes)	$ 0	$ (56)	$ (39)	$ (24)