Regulatory Assets and Liabilities, Regulatory Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 44	$ 21
Regulatory Asset, Noncurrent		193	225
Environmental Remediation Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		13	13	[1]
Regulatory Asset, Noncurrent		63	79	[1]
Pension and Retiree Medical Obligations
Regulatory Assets [Line Items]
Regulatory Asset, Current		2	4	[1]
Regulatory Asset, Noncurrent		61	55	[1]
Deferred Fuel Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		23	2	[1]
Regulatory Asset, Noncurrent		$ 0	29	[1]
Deferred Fuel Costs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
State Commission Adjustments
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 1	1	[1]
Regulatory Asset, Noncurrent		22	21	[1]
Recoverable Deferred Taxes on AFUDC Recorded in Plant
Regulatory Assets [Line Items]
Regulatory Asset, Current		0	0	[1]
Regulatory Asset, Noncurrent		20	19	[1]
Asset Retirement Obligation Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current	[2]	0	0	[1]
Regulatory Asset, Noncurrent	[2]	18	10	[1]
Other
Regulatory Assets [Line Items]
Regulatory Asset, Current		5	1	[1]
Regulatory Asset, Noncurrent		$ 9	$ 12	[1]

[1] Prior period amounts have been restated to conform with current year presentation.

[2] Includes amounts recorded for future recovery of AROs, less amounts recovered through NSP-Wisconsin’s share of nuclear decommissioning accruals and gains from decommissioning investments.