Exit Activities and Discontinued Operations - Income from Discontinued Operations (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale1				$ 5	$ 0
Income tax expense		$ 0	$ 7	1	16
Income from discontinued operations, net of tax		0	18	4	52
Discontinued Operations, Held-for-sale | EnerBank
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenue		0	69	0	139
Operating expenses		0	28	0	43
Interest expense		0	11	0	23
Income before income taxes		0	30	0	73
Gain on sale1	$ 657	0	(5)	5	(5)
Income from discontinued operations before income taxes		0	25	5	68
Income tax expense		0	7	1	16
Income from discontinued operations, net of tax		$ 0	$ 18	$ 4	$ 52