Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of derivative assets and liabilities

None of our derivatives are designated as hedging instruments, with the exception of interest rate swaps, which were designated as cash flow hedges. Derivative assets and liabilities are included in the other current and other long-term line items on our balance sheets. The following table shows our derivative assets and derivative liabilities.

	December 31, 2021				December 31, 2020
(in millions)	Derivative Assets		Derivative Liabilities		Derivative Assets		Derivative Liabilities
Current
Natural gas contracts	$	60.6	$	14.0	$	13.0	$	12.9
FTRs	2.4		—		2.4		—
Coal contracts	44.0		—		1.6		0.8
Interest rate swaps	—		—		—		6.8
Total current	107.0		14.0		17.0		20.5
Long-term
Natural gas contracts	4.0		1.1		0.7		1.2
Coal contracts	9.0		—		0.2		0.4
Total long-term	13.0		1.1		0.9		1.6
Total	$	120.0	$	15.1	$	17.9	$	22.1

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

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

	December 31, 2021			December 31, 2020			December 31, 2019
(in millions)	Volumes	Gains		Volumes	Gains (Losses)		Volumes	Gains (Losses)
Natural gas contracts	197.6 Dth	$	136.5	188.6 Dth	$	(54.1)	183.9 Dth	$	(27.1)
FTRs	28.2 MWh	17.7		29.8 MWh	4.1		31.2 MWh	16.3
Total		$	154.2		$	(50.0)		$	(10.8)

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, 2021						December 31, 2020
(in millions)	Derivative Assets			Derivative Liabilities			Derivative Assets		Derivative Liabilities
Gross amount recognized on the balance sheet	$	120.0		$	15.1		$	17.9	$	22.1
Gross amount not offset on the balance sheet	(15.2)		(1)	(9.2)		(2)	(6.9)		(7.7)		(3)
Net amount	$	104.8		$	5.9		$	11.0	$	14.4

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

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

(3)    Includes cash collateral posted of $0.8 million.

Schedule of cash flow hedges recorded in other comprehensive 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)	2021		2020		2019
Derivative gain (loss) recognized in other comprehensive income / loss	$	0.8	$	(5.9)	$	(4.8)
Net derivative gain (loss) reclassified from accumulated other comprehensive loss to interest expense	(1.3)		(2.1)		1.1
Total interest expense line item on the income statements	471.1		493.7		501.5