Income Taxes - Reconciliation of Federal Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income from Continuing Operations, before income taxes	$ 449	$ 504	$ 1,061	$ 1,080
Federal income tax expense at statutory rate (21%)	94	106	223	227
Increases (reductions) in taxes resulting from:
State income taxes, net of federal tax benefit	25	31	68	80
AFUDC equity and other flow-through	(8)	(9)	(23)	(26)
Excess deferred tax amortization due to the Tax Act	(15)	(13)	(46)	(39)
Federal tax credits claimed	(3)	(6)	(3)	(34)
Valuation allowances	(8)	0	26	0
Remeasurement of state deferred taxes	4	0	(22)	9
Nondeductible DPA monetary penalty	0	0	0	52
Uncertain tax positions	2	(25)	2	(19)
Other, net	14	4	12	21
Income taxes (benefits)	$ 105	$ 88	$ 237	$ 271
Effective income tax rate	23.40%	17.50%	22.30%	25.10%