Fair Value of Financial Assets and Liabilities - Interest Rate Derivatives (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Interest Rate Swap
Derivative [Line Items]
Derivative Liability, Notional Amount		$ 0	$ 0
Natural Gas Commodity | Other Derivative Instruments | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Asset, Net	[1]	1	1
Natural Gas Commodity | Other Derivative Instruments | Other Current Assets | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Asset, Gross		1	1
Netting	[2]	0	0
Natural Gas Commodity | Other Derivative Instruments | Other Current Assets | Level 1 | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Asset, Gross		0	0
Natural Gas Commodity | Other Derivative Instruments | Other Current Assets | Level 2 | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Asset, Gross		1	1
Natural Gas Commodity | Other Derivative Instruments | Other Current Assets | Level 3 | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Asset, Gross		$ 0	$ 0

[1] Included in prepayments and other current assets at Sept. 30, 2022 and Dec. 31, 2021 on the consolidated balance sheets.

[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 amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.