Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative assets and derivative liabilities

The following table shows our derivative assets and derivative liabilities:

		September 30, 2015				December 31, 2014
(in millions)	Balance Sheet Presentation	Derivative Assets		Derivative Liabilities		Derivative Assets		Derivative Liabilities
Natural gas	Other current	$	6.1	$	33.0	$	5.0	$	11.5
Natural gas	Other long-term	0.4		3.5		—		0.8
Petroleum products	Other current	0.2		1.7		—		—
Petroleum products	Other long-term	0.2		0.4		—		—
FTRs	Other current	5.8		—		7.0		—
Coal	Other current	0.8		5.2		2.7		0.2
Coal	Other long-term	—		2.7		0.6		—
	Other current	12.9		39.9		14.7		11.7
	Other long-term	0.6		6.6		0.6		0.8
Total		$	13.5	$	46.5	$	15.3	$	12.5

Estimated notional volumes and gain (losses)

Our estimated notional sales volumes and gains (losses) were as follows:

	Three Months Ended September 30, 2015				Three Months Ended September 30, 2014
(in millions)	Volume	Gains (Losses)			Volume	Gains (Losses)
Natural gas	24.2 Dth	$	(13.2	)	6.3 Dth	$	(0.8	)
Petroleum products	2.8 gallons	(0.9		)	2.6 gallons	—
FTRs	8.6 MWh	3.1			6.6 MWh	2.0
Total		$	(11.0	)		$	1.2

	Nine Months Ended September 30, 2015				Nine Months Ended September 30, 2014
(in millions)	Volume	Gains (Losses)			Volume	Gains
Natural gas	47.5 Dth	$	(26.2	)	31.1 Dth	$	9.3
Petroleum products	4.5 gallons	(0.9		)	7.0 gallons	0.6
FTRs	20.7 MWh	6.0			19.7 MWh	11.6
Total		$	(21.1	)		$	21.5

Offsetting assets and liabilities

The following table shows derivative assets and derivative liabilities if derivative instruments by counterparty were presented net on the condensed consolidated balance sheet:

	September 30, 2015						December 31, 2014
	Derivative			Derivative			Derivative			Derivative
(in millions)	Assets			Liabilities			Assets			Liabilities
Gross amount recognized on the balance sheet	$	13.5		$	46.5		$	15.3		$	12.5
Gross amount not offset on balance sheet *	(5.0		)	(19.2		)	(0.4		)	(11.5		)
Net Amount	$	8.5		$	27.3		$	14.9		$	1.0

* Includes cash collateral posted of $14.2 million and $10.3 million as of September 30, 2015, and December 31, 2014, respectively.