Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of derivative assets and liabilities

None of the derivatives shown below were designated as hedging instruments.

	December 31, 2022				December 31, 2021
(in millions)	Derivative Assets		Derivative Liabilities		Derivative Assets		Derivative Liabilities
Current
Natural gas contracts	$	32.5	$	88.2	$	60.6	$	14.0
FTRs	7.8		—		2.4		—
Coal contracts	18.9		—		44.0		—
Total current	59.2		88.2		107.0		14.0
Long-term
Natural gas contracts	—		8.4		4.0		1.1
Coal contracts	15.6		—		9.0		—
Total long-term	15.6		8.4		13.0		1.1
Total	$	74.8	$	96.6	$	120.0	$	15.1

Schedule of estimated notional sales volumes and realized gains (losses)

Our estimated notional sales volumes and realized gains and losses were as follows for the years ended:

	December 31, 2022			December 31, 2021			December 31, 2020
(in millions)	Volumes	Gains		Volumes	Gains		Volumes	Gains (Losses)
Natural gas contracts	183.3 Dth	$	299.5	197.6 Dth	$	136.5	188.6 Dth	$	(54.1)
FTRs and TCRs	27.2 MWh	11.8		28.2 MWh	17.7		29.8 MWh	4.1
Total		$	311.3		$	154.2		$	(50.0)

Schedule of net derivative instruments

The following table shows derivative assets and derivative liabilities if derivative instruments by counterparty were presented net on our balance sheets:

	December 31, 2022					December 31, 2021
(in millions)	Derivative Assets		Derivative Liabilities			Derivative Assets			Derivative Liabilities
Gross amount recognized on the balance sheet	$	74.8	$	96.6		$	120.0		$	15.1
Gross amount not offset on the balance sheet	(17.5)		(82.5)		(1)	(15.2)		(2)	(9.2)		(3)
Net amount	$	57.3	$	14.1		$	104.8		$	5.9

(1)    Includes cash collateral posted of $65.0 million.

(2)    Includes cash collateral received of $6.4 million.

(3)    Includes cash collateral posted of $0.4 million.

Schedule of cash flow hedges recorded in other comprehensive income (loss) and earnings

The table below shows the amounts related to these cash flow hedges recorded in other comprehensive income (loss) and in earnings, along with our total interest expense on the income statements, for the years ended December 31:

(in millions)	2022		2021		2020
Derivative gain (loss) recognized in other comprehensive income / loss	$	—	$	0.8	$	(5.9)
Net derivative gain (loss) reclassified from accumulated other comprehensive loss to interest expense	0.4		(1.3)		(2.1)
Total interest expense line item on the income statements	515.1		471.1		493.7