Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Taxes [Line Items]
Income tax expense (benefit)	$ 95	$ 98	$ 229	$ 274
Income tax (benefit) expense from discontinued operations	(19)	38	32	94
East Ohio
Income Taxes [Line Items]
Income tax expense (benefit)			11
Discontinued operations, deferred tax liabilities	29		29
East Ohio, PSNC and Questar Gas
Income Taxes [Line Items]
Discontinued operations, deferred tax liabilities	825		825
Questar Gas and Wexpro
Income Taxes [Line Items]
Income tax expense (benefit)			(75)
Discontinued operations, deferred tax liabilities	462		462
PSNC Transaction
Income Taxes [Line Items]
Income tax expense (benefit)			16
Virginia Electric and Power Company
Income Taxes [Line Items]
Income tax expense (benefit)	$ 117	$ 86	245	$ 183
Production tax credit			$ 17