Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

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

Recurring Derivative Fair Value Measurements

Impact of derivative activity:

Changes in the fair value of natural gas commodity derivatives resulted in immaterial net losses and gains for the three and nine months ended Sept. 30, 2023 and 2022, which were recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

During the three and nine months ended Sept. 30, 2023 and 2022, there were immaterial natural gas commodity derivatives settlement losses and gains. During the three and nine months ended Sept. 30, 2023 and 2022, immaterial pre-tax losses were recognized during the period in income related to option premium amortization.

NSP-Wisconsin had immaterial outstanding derivative assets or liabilities measured at fair value as of Sept. 30, 2023 and Dec. 31, 2022.

Carrying Amount and Fair Value of Long-term Debt

	Sept. 30, 2023				Dec. 31, 2022
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	1,211	$	1,062	$	1,086	$	980