Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level

	Dec. 31, 2022												Dec. 31, 2021
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative assets (b)
Natural gas commodity	$	—	$	2	$	—	$	2	$	—	$	2	$	—	$	1	$	—	$	1	$	—	$	1
Current derivative liabilities (c)
Natural gas commodity	$	—	$	1	$	—	$	1	$	—	$	1	$	—	$	1	$	—	$	1	$	—	$	1

(a)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.

(b)Included in prepayments and other current assets at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet.

(c)Included in other current liabilities at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet.

Carrying Amount and Fair Value of Long-term Debt

As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value:

	2022				2021
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	1,086	$	980	$	987	$	1,143

Derivative Instruments, Gain (Loss)

Pre-Tax Fair Value Gains (Losses) Recognized During the Period in:
(Millions of Dollars)	Regulatory (Assets) and Liabilities
Year Ended Dec. 31, 2022
Other derivative instruments
Natural gas commodity	(1)
Total	$	(1)
Year Ended Dec. 31, 2021
Other derivative instruments
Natural gas commodity	(1)
Total	$	(1)
Year Ended Dec. 31, 2020
Other derivative instruments
Natural gas commodity	(1)
Total	$	(1)

Pre-Tax (Gains) Losses Reclassified into Income During the Period from:				Pre-Tax Gains (Losses) Recognized During the Period in Income
(Millions of Dollars)	Regulatory Assets and (Liabilities)
Year Ended Dec. 31, 2022
Other derivative instruments
Natural gas commodity	—			(2)		(a)
Total	$	—		$	(2)
Year Ended Dec. 31, 2021
Other derivative instruments
Natural gas commodity	—			(1)		(a)
Total	$	—		$	(1)
Year Ended Dec. 31, 2020
Other derivative instruments
Natural gas commodity	1		(a)	(1)		(a)
Total	$	1		$	(1)

(a)    Recorded to cost of natural gas sold and transported. These losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.