Accumulated Other Comprehensive Income (Loss) - After-tax Changes by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (152)	$ (3,882)	$ (157)	$ (4,220)
Amounts arising during the period	22	54	22	327
Reclassifications from AOCI	6	59	11	124
Net OCI during the period	28	3,691	33	4,029
Balance at end of period	(124)	(191)	(124)	(191)
Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications from AOCI		3,578		3,578
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	0	(855)	0	(1,158)
Amounts arising during the period	0	69	0	372
Reclassifications from AOCI	0	0	0	0
Net OCI during the period	0	855	0	1,158
Balance at end of period	0	0	0	0
Foreign currency translation adjustments [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications from AOCI		786		786
Unrealized gains (losses) on qualifying derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	2	(5)	1	0
Amounts arising during the period	0	(9)	0	(39)
Reclassifications from AOCI	0	(1)	1	24
Net OCI during the period	0	5	1	0
Balance at end of period	2	0	2	0
Unrealized gains (losses) on qualifying derivatives [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications from AOCI		15		15
Defined benefit plans Prior service costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(6)	(16)	(6)	(16)
Amounts arising during the period	0	0	(1)	0
Reclassifications from AOCI	0	(7)	1	(7)
Net OCI during the period	0	1	0	1
Balance at end of period	(6)	(15)	(6)	(15)
Defined benefit plans Prior service costs [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications from AOCI		8		8
Defined benefit plans Actuarial gain (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(149)	(3,006)	(152)	(3,046)
Amounts arising during the period	21	(6)	21	(6)
Reclassifications from AOCI	6	67	9	107
Net OCI during the period	27	2,830	30	2,870
Balance at end of period	(122)	(176)	(122)	(176)
Defined benefit plans Actuarial gain (loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications from AOCI		2,769		2,769
Equity Investees' OCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	1	0	0	0
Amounts arising during the period	1	0	2	0
Reclassifications from AOCI	0	0	0	0
Net OCI during the period	1	0	2	0
Balance at end of period	$ 2	0	$ 2	0
Equity Investees' OCI | Reclassification out of Accumulated Other Comprehensive Income (Loss) due to Sale of U.K. Utility Business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications from AOCI		$ 0		$ 0