Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Gross Notional Amounts of Commodity Forwards and Options

Gross notional amounts of commodity options:

(Amounts in Millions) (a)(b)	Sept. 30, 2020	Dec. 31, 2019
Million British thermal units of natural gas	1.0	0.1

(a)Amounts are not reflective of net positions in the underlying commodities.

(b)Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

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

Recurring Fair Value Measurements — NSP-Wisconsin's derivative assets measured at fair value on a recurring basis were as follows:

	Sept. 30, 2020
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	0.8	$	—	$	0.8	$	—	$	0.8

	Dec. 31, 2019
	Fair Value						Fair Value Total		Netting (a)		Total (b)
(Millions of Dollars)	Level 1		Level 2		Level 3
Current derivative assets
Natural gas commodity	$	—	$	0.5	$	—	$	0.5	$	—	$	0.5

(a)    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 Sept. 30, 2020 and Dec. 31, 2019. The counterparty netting amounts presented exclude 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 balance of $6.3 million at Sept. 30, 2020 and $4.6 million at Dec. 31, 2019 on the consolidated balance sheets.

Carrying Amount and Fair Value of Long-term Debt

Other financial instruments for which the carrying amount did not equal fair value:

	Sept. 30, 2020				Dec. 31, 2019
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	906.0	$	1,154.0	$	808.0	$	924.3