Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative instruments in balance sheet

We record our current derivative assets on the balance sheet in other current assets and the current portion of the liabilities in other current liabilities. The long-term portion of our derivative assets of $0.6 million is recorded in other deferred charges and other assets, and the long-term portion of our derivative liabilities of $0.8 million is recorded in other deferred credit and other liabilities. Our Consolidated Balance Sheets as of December 31, 2014 and 2013 include:

	December 31, 2014				December 31, 2013
	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
	(Millions of Dollars)
Natural Gas	$	5.0	$	12.3	$	5.6	$	0.1
Fuel Oil	—		—		0.6		—
FTRs	7.0		—		3.5		—
Coal	3.3		0.2		2.1		0.2
Total	$	15.3	$	12.5	$	11.8	$	0.3

Derivative instruments' estimated notional volumes and gain (losses)

Our Consolidated Income Statements include gains (losses) on derivative instruments used in our risk management strategies under fuel and purchased power for those commodities supporting our electric operations and under cost of gas sold for the natural gas sold to our customers. Our estimated notional volumes and gains (losses) for the years ended December 31 were as follows:

	2014			2013
	Volume	Gains		Volume	Gains (Losses)
		(Millions of Dollars)			(Millions of Dollars)
Natural Gas	40.5 million Dth	$	7.3	48.6 million Dth	$	(8.5	)
Fuel Oil	9.2 million gallons	0.5		8.6 million gallons	0.5
FTRs	26.1 million MWh	12.7		25.3 million MWh	14.9
Total		$	20.5		$	6.9

Offsetting Assets and Liabilities [Table Text Block]

	2014						2013
	Derivative			Derivative			Derivative		Derivative
	Asset			Liability			Asset		Liability
	(Millions of Dollars)
Gross Amount Recognized on the Balance Sheet	$	15.3		$	12.5		$	11.8	$	0.3
Gross Amount Not Offset on Balance Sheet (a)	(0.4		)	(11.5		)	—		—
Net Amount	$	14.9		$	1.0		$	11.8	$	0.3

(a) Gross Amount Not Offset on Balance Sheet includes cash collateral posted of $10.3 million and zero as of December 31, 2014 and 2013, respectively.