Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2012

Derivative Instruments (Tables) [Abstract]

Derivative instruments in balance sheet

	September 30, 2012				December 31, 2011
	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
	(Millions of Dollars)
Natural Gas	$	12.0	$	—	$	2.1	$	9.1
Fuel Oil	0.9		—		0.3		0.1
FTRs	7.3		—		5.7		—
Coal	11.0		2.1		12.5		—
Total	$	31.2	$	2.1	$	20.6	$	9.2

Derivative instruments' estimated notional volumes and gain (losses)

	Three Months Ended September 30, 2012				Three Months Ended September 30, 2011
	Volume	Gains (Losses)			Volume	Gains (Losses)
		(Millions of Dollars)				(Millions of Dollars)
Natural Gas	17.2 million Dth	$	(5.3	)	15.7 million Dth	$	(10.5	)
Fuel Oil	1.7 million gallons	0.1			2.2 million gallons	2.4
FTRs	5,927 MW	2.9			5,896 MW	5.2
Total		$	(2.3	)		$	(2.9	)

	Nine Months Ended September 30, 2012				Nine Months Ended September 30, 2011
	Volume	Gains (Losses)			Volume	Gains (Losses)
		(Millions of Dollars)				(Millions of Dollars)
Natural Gas	56.0 million Dth	$	(35.7	)	54.0 million Dth	$	(27.7	)
Fuel Oil	5.5 million gallons	1.5			8.8 million gallons	4.9
FTRs	16,581 MW	5.1			18,439 MW	10.5
Total		$	(29.1	)		$	(12.3	)