Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Derivative Instruments (Tables) [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 we had no long-term portion of derivative liabilities. Our Consolidated Balance Sheets as of December 31, 2012 and 2011 include:

	December 31, 2012				December 31, 2011
	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
	(Millions of Dollars)
Natural Gas	$	1.7	$	0.5	$	2.1	$	9.1
Fuel Oil	0.4		—		0.3		0.1
FTRs	4.7		—		5.7		—
Coal	11.1		—		12.5		—
Total	$	17.9	$	0.5	$	20.6	$	9.2

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:

	2012				2011
	Volume	Gains (Losses)			Volume	Gains (Losses)
		(Millions of Dollars)				(Millions of Dollars)
Natural Gas	77.2 million Dth	$	(36.3	)	71.8 million Dth	$	(33.4	)
Fuel Oil	7.0 million gallons	1.8			13.0 million gallons	6.9
FTRs	20,616 MW	6.1			23,718 MW	12.5
Total		$	(28.4	)		$	(14.0	)