Fair Value of Financial Assets and Liabilities - Interest Rate Derivatives (Details) - Natural Gas Commodity - Other Derivative Instruments - Fair Value, Recurring [Member] - USD ($) $ in Millions		Mar. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative Asset, Net		$ 0	$ 2	[1]
Other Current Assets
Derivative [Line Items]
Derivative Asset, Gross	[1]		2
Netting	[1],[2]		0
Other Current Assets | Level 1
Derivative [Line Items]
Derivative Asset, Gross	[1]		0
Other Current Assets | Level 2
Derivative [Line Items]
Derivative Asset, Gross	[1]		2
Other Current Assets | Level 3
Derivative [Line Items]
Derivative Asset, Gross	[1]		$ 0

[1] $2 million included in prepayments and other current assets and $1 million included in other current liabilities at Dec. 31, 2022 on the consolidated balance sheet.

[2] NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement. Counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.