Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2011

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 $2.5 million is recorded in other deferred charges and other assets, and the long-term portion of our derivative liabilities of $0.7 million is recorded in other long-term liabilities. Our Consolidated Balance Sheets as of December 31, 2011 and 2010 include:

	December 31, 2011				December 31, 2010
	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
	(Millions of Dollars)
Natural Gas	$	2.1	$	9.1	$	2.5	$	11.6
Fuel Oil	0.3		0.1		4.4		—
FTRs	5.7		—		5.9		—
Coal	12.5		—		2.9		—
Total	$	20.6	$	9.2	$	15.7	$	11.6

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:

	2011				2010
	Volume	Gains (Losses)			Volume	Gains (Losses)
		(Millions of Dollars)				(Millions of Dollars)
Natural Gas	71.8 million Dth	$	(33.4	)	83.2 million Dth	$	(43.8	)
Power	zero MWh	—			234,720 MWh	(0.5		)
Fuel Oil	13.0 million gallons	6.9			8.1 million gallons	(0.5		)
FTRs	23,718 MW	12.5			25,234 MW	19.2
Total		$	(14.0	)		$	(25.6	)