Recurring Fair Value Measurement (Details) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Prepayments and other		$ 7	$ 7
Other Liabilities, Noncurrent		32	27
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		1	1
Netting	[1]	0	0
Derivative Asset, Net	[2]	1	1
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		1	1
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity Contract | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0	$ 0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Natural Gas Commodity Contract
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		1
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1]	0
Derivative Liability	[3]	1
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Natural Gas Commodity Contract | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Natural Gas Commodity Contract | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		1
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Natural Gas Commodity Contract | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		$ 0

[1] NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2021 and Dec. 31, 2020. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[2] Included in prepayments and other current assets balance of $7 million at Dec. 31, 2021 and Dec. 31, 2020 on the consolidated balance sheets, respectively.

[3] Included in other current liabilities balance of $1 million at Dec. 31, 2021 on the consolidated balance sheets