Benefit Plans and Other Postretirement Benefits (Details) - Pension Plan [Member] $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended
		Jan. 31, 2022 USD ($) Plan	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Components of Net Periodic Benefit Cost [Abstract]
Service cost			$ 2	$ 1	$ 4	$ 4
Interest cost (a)	[1]		1	1	3	3
Expected return on plan assets (a)	[1]		(2)	(2)	(6)	(6)
Amortization of net loss (a)	[1]		1	2	3	4
Net periodic benefit cost			6	5	8	8
Effects of regulation			(2)	(2)	(2)	(2)
Net benefit cost recognized for financial reporting			4	3	6	6
Contributions to pension plans		$ 1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	[2]		$ 4	$ 3	$ 4	$ 3
Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 50
Number of Xcel Energy's pension plans to which contributions were made | Plan		4

[1] The components of net periodic cost other than the service cost component are included in the line item “Other expense, net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.(b)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 the third quarter of 2022 and 2021 as a result of lump-sum distributions during the 2022 and 2021 plan years, NSP-Wisconsin recorded pension settlement charges of $4 million and $3 million, respectively, the majority of which were not recognized in earnings due to the effects of regulation.

[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 the third quarter of 2022 and 2021 as a result of lump-sum distributions during the 2022 and 2021 plan years, NSP-Wisconsin recorded pension settlement charges of $4 million and $3 million, respectively, the majority of which were not recognized in earnings due to the effects of regulation.