Segment Information - MEC (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) reportableSegment operatingSegment	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | operatingSegment			8
Operating revenue	$ 6,229	$ 6,612	$ 12,575	$ 12,642
Operating income (loss)	1,046	1,207	1,713	2,443
Interest expense	(599)	(550)	(1,185)	(1,082)
Allowance for equity funds	61	42	110	80
Other, net	78	(26)	118	(21)
Income (loss) before income tax expense (benefit) and equity income (loss)	1,049	3,249	2,028	2,779
Assets	137,751		$ 137,751		$ 133,840
MEC
Segment Reporting Information [Line Items]
Number of reportable segments | reportableSegment			2
Operating revenue	759	897	$ 1,679	1,902
Operating income (loss)	118	90	206	190
Interest expense	(81)	(78)	(161)	(156)
Allowance for borrowed funds	4	5	8	9
Allowance for equity funds	13	14	24	29
Other, net	15	(12)	31	(15)
Income (loss) before income tax expense (benefit) and equity income (loss)	69	19	108	57
Assets	24,143		24,143		23,978
MEC | Regulated electric
Segment Reporting Information [Line Items]
Operating revenue	661	725	1,252	1,333
Operating income (loss)	120	87	170	138
Assets	22,425		22,425		22,092
MEC | Regulated natural gas
Segment Reporting Information [Line Items]
Operating revenue	97	171	423	567
Operating income (loss)	(2)	3	36	52
Assets	1,717		1,717		1,885
MEC | Other
Segment Reporting Information [Line Items]
Operating revenue	1	$ 1	4	$ 2
Assets	$ 1		$ 1		$ 1