Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of derivative assets and liabilities

The following table shows our derivative assets and derivative liabilities, along with their classification on our balance sheets. None of our derivatives are designated as hedging instruments, with the exception of our interest rate swaps, which have been designated as cash flow hedges.

	December 31, 2019				December 31, 2018
(in millions)	Derivative Assets		Derivative Liabilities		Derivative Assets		Derivative Liabilities
Other current
Natural gas contracts	$	3.4	$	21.8	$	7.7	$	5.3
FTRs	3.1		—		7.4		—
Coal contracts	0.2		0.2		0.2		0.1
Interest rate swaps	—		2.8		—		0.4
Total other current	6.7		24.8		15.3		5.8
Other long-term
Natural gas contracts	—		0.9		0.4		0.2
Coal contracts	0.2		—		0.2		—
Interest rate swaps	—		3.2		—		1.9
Total other long-term	0.2		4.1		0.6		2.1
Total	$	6.9	$	28.9	$	15.9	$	7.9

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, 2019				December 31, 2018			December 31, 2017
(in millions)	Volumes	Gains (Losses)			Volumes	Gains		Volumes	Gains (Losses)
Natural gas contracts	183.9 Dth	$	(27.1	)	173.2 Dth	$	24.6	123.1 Dth	$	(8.0	)
Petroleum products contracts	— gallons	—			6.0 gallons	1.6		18.0 gallons	(1.3		)
FTRs	31.2 MWh	16.3			30.5 MWh	15.9		36.2 MWh	14.0
Total		$	(10.8	)		$	42.1		$	4.7

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, 2019							December 31, 2018
(in millions)	Derivative Assets			Derivative Liabilities				Derivative Assets				Derivative Liabilities
Gross amount recognized on the balance sheet	$	6.9		$	28.9			$	15.9			$	7.9
Gross amount not offset on the balance sheet	(1.4		)	(21.4		)	(1)	(4.0		)	(2)	(4.9		)	(3)
Net amount	$	5.5		$	7.5			$	11.9			$	3.0

⁽¹⁾  Includes cash collateral posted of $20.0 million.

⁽²⁾ Includes cash collateral received of $0.2 million.

⁽³⁾ 

Includes cash collateral posted of $1.1 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 loss and in earnings, along with our total interest expense on the income statements, for the years ended December 31:

(in millions)	2019			2018			2017
Derivative losses recognized in other comprehensive loss	$	(4.8	)	$	(2.9	)	$	—
Net derivative gains reclassified from accumulated other comprehensive loss to interest expense	1.1			1.6			2.2
Total interest expense line item on the income statements	501.5			445.1			415.7