Other Income Tax Matters (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Income Tax Examination [Line Items]
Tax Credit Carryforward, Amount		$ 3	$ 7
State NOL carryforward		$ 2	$ 2
Federal statutory rate		21.00%	21.00%		21.00%
State income tax on pretax income, net of federal tax effect		6.20%	6.20%		6.20%
Plant regulatory differences (a)	[1]	(3.40%)	(3.80%)		(4.10%)
Other tax credits, net NOL & tax credit allowances		(0.60%)	(0.80%)		(1.00%)
Other, net		(0.50%)	(0.70%)		(0.40%)
Effective income tax rate		22.70%	21.90%		21.70%
Total income tax expense		$ 40	$ 35		$ 30
Deferred tax (benefit) expense excluding items below		(3)	8		18
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities		(10)	(10)		(10)
Deferred tax (benefit) expense		12	2		9
Environmental remediation		4	4	[2]
Other		1	0		1
Deferred Finance Costs, Noncurrent, Net		11	11
Credit Facilities
Income Tax Examination [Line Items]
Long-term Line of Credit		0	0
income tax expense [Member]
Income Tax Examination [Line Items]
Current federal tax expense		37	28		17
Current state tax expense		15	9		4
Deferred federal tax (benefit) expense		(10)	(5)		3
Deferred state tax (benefit) expense		(3)	3		6
Total income tax expense		40	35		30
Deferred Change In Unrecognized Tax Expense Benefit		1	0		$ 0
Net Deferred Tax Liablility [Member]
Income Tax Examination [Line Items]
Tax Credit Carryforward, Amount		3	7	[2]
Deferred tax (benefit) expense		59	58	[2]
Difference between book and tax bases of property		350	343	[2]
Regulatory assets		22	24	[2]
Pension expense		10	10	[2]
Deferred fuel costs		0	6	[2]
Other		7	8	[2]
Total deferred tax liabilities		389	391	[2]
Regulatory liabilities		32	35	[2]
Other employee benefits		4	3	[2]
Deferred Tax Assets Rate Refund		10	3	[2]
Deferred ITCs		2	2	[2]
Other		4	4	[2]
Net deferred tax liability		$ 330	$ 333	[2]

[1] Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

[2] Prior periods have been reclassified to conform to current year presentation