Benefit Plans and Other Postretirement Benefits, Postretirement Benefit Plan Benefit Obligations, Cash Flows and Benefit Costs (Details) - USD ($)		1 Months Ended		12 Months Ended
		Jan. 31, 2023		Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Funded Status of Plans at Dec. 31 [Abstract]
Noncurrent liabilities				$ (23,000,000)		$ (16,000,000)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits		$ 50,000,000
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		112,000,000		141,000,000		154,000,000
Service cost				5,000,000		5,000,000	$ 4,000,000
Interest cost				4,000,000		4,000,000	5,000,000
Actuarial loss				(21,000,000)		(4,000,000)
Benefit payments				(17,000,000)		(18,000,000)
Obligation at Dec. 31				112,000,000		141,000,000	154,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		97,000,000	[1]	137,000,000		140,000,000
Actual return (loss) on plan assets				(24,000,000)		10,000,000
Employer contributions				1,000,000		5,000,000
Benefit payments				(17,000,000)		(18,000,000)
Fair value of plan assets at Dec. 31				97,000,000	[1]	137,000,000	140,000,000
Funded Status of Plans at Dec. 31 [Abstract]
Funded status				(15,000,000)		(4,000,000)
Current liabilities				0		0
Noncurrent liabilities				(15,000,000)		(4,000,000)
Net postretirement amounts recognized on consolidated balance sheets				(15,000,000)		(4,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss				45,000,000		44,000,000
Prior service (credit) cost				0		0
Total				45,000,000		44,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets				1,000,000		4,000,000
Noncurrent regulatory assets				44,000,000		40,000,000
Total				$ 45,000,000		$ 44,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)				5.80%		3.08%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase				4.25%		3.75%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				$ 5,000,000		$ 5,000,000	4,000,000
Interest cost				4,000,000		4,000,000	5,000,000
Expected return on plan assets				(8,000,000)		(8,000,000)	(8,000,000)
Amortization of net loss				3,000,000		5,000,000	5,000,000
Settlement charge	[2]			6,000,000		5,000,000	0
Net periodic benefit cost				$ 10,000,000		$ 11,000,000	$ 6,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)				3.08%		2.71%	3.49%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase				3.75%		3.75%	3.75%
Expected average long-term rate of return on assets (as a percent)				6.60%		6.60%	7.10%
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation				$ 2,000,000		$ (3,000,000)	$ 7,000,000
Net benefit cost recognized for financial reporting				8,000,000		8,000,000	13,000,000
Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		8,000,000		11,000,000		13,000,000
Service cost				0		0	0
Interest cost				1,000,000		1,000,000	1,000,000
Actuarial loss				(3,000,000)		(1,000,000)
Benefit payments				(1,000,000)		(2,000,000)
Obligation at Dec. 31				8,000,000		11,000,000	13,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		$ 0		0		0
Actual return (loss) on plan assets				0		0
Employer contributions				1,000,000		1,000,000
Benefit payments				(1,000,000)		(1,000,000)
Fair value of plan assets at Dec. 31				0		0	0
Funded Status of Plans at Dec. 31 [Abstract]
Funded status				(8,000,000)		(11,000,000)
Current liabilities				0		(1,000,000)
Noncurrent liabilities				(8,000,000)		(10,000,000)
Net postretirement amounts recognized on consolidated balance sheets				(8,000,000)		(11,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss				4,000,000		6,000,000
Prior service (credit) cost				0		0
Total				4,000,000		6,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets				0		0
Noncurrent regulatory assets				4,000,000		6,000,000
Total				$ 4,000,000		$ 6,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)				5.80%		3.09%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65				6.50%		5.30%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65				5.50%		4.90%
Ultimate health care trend assumption rate (as a percent)				4.50%		4.50%
Period until ultimate trend rate is reached (in years)				$ 7		$ 4
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				0		0	0
Interest cost				1,000,000		1,000,000	1,000,000
Expected return on plan assets				0		0	0
Amortization of net loss				0		0	0
Settlement charge	[2]			0		0	0
Net periodic benefit cost				$ 1,000,000		$ 1,000,000	$ 1,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)				3.09%		2.65%	3.47%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase				0.00%		0.00%	0.00%
Expected average long-term rate of return on assets (as a percent)				4.10%		4.10%	4.50%
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation				$ 0			$ 0
Net benefit cost recognized for financial reporting				$ 1,000,000		$ 1,000,000	$ 1,000,000

[1] See Note 8 for further information on fair value measurement inputs and methods.

[2] A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020.