Derivative Instruments (Tables)

6 Months Ended

Jun. 30, 2013

Derivative [Line Items]

Offsetting Assets and Liabilities [Table Text Block]

	June 30, 2013						December 31, 2012
	Derivative			Derivative			Derivative			Derivative
	Asset			Liability			Asset			Liability
	(Millions of Dollars)
Gross Amount Recognized on the Balance Sheet	$	18.5		$	1.7		$	19.2		$	1.9
Gross Amount Not Offset on Balance Sheet (a)	(0.1		)	(1.7		)	(0.5		)	(1.8		)
Net Amount	$	18.4		$	—		$	18.7		$	0.1

(a) Gross Amount Not Offset on Balance Sheet includes cash collateral posted of $1.6 million and $1.3 million as of June 30, 2013 and December 31, 2012, respectively.

Derivative instruments in balance sheet

	June 30, 2013				December 31, 2012
	Derivative Asset		Derivative Liability		Derivative Asset		Derivative Liability
	(Millions of Dollars)
Natural Gas	$	2.1	$	1.5	$	3.0	$	1.9
Fuel Oil	0.1		0.2		0.4		—
FTRs	9.2		—		4.7		—
Coal	7.1		—		11.1		—
Total	$	18.5	$	1.7	$	19.2	$	1.9

Derivative instruments' estimated notional volumes and gain (losses)

	Three Months Ended June 30, 2013			Three Months Ended June 30, 2012
	Volume	Gains (Losses)		Volume	Gains (Losses)
		(Millions of Dollars)			(Millions of Dollars)
Natural Gas	11.3 million Dth	$	1.9	18.5 million Dth	$	(14.2	)
Fuel Oil	2.2 million gallons	0.1		2.1 million gallons	0.8
FTRs	5,744 MW	4.7		5,296 MW	1.6
Total		$	6.7		$	(11.8	)

	Six Months Ended June 30, 2013				Six Months Ended June 30, 2012
	Volume	Gains (Losses)			Volume	Gains (Losses)
		(Millions of Dollars)				(Millions of Dollars)
Natural Gas	30.1 million Dth	$	(4.6	)	38.9 million Dth	$	(30.4	)
Fuel Oil	3.7 million gallons	0.2			3.8 million gallons	1.4
FTRs	11,088 MW	5.6			10,654 MW	2.2
Total		$	1.2			$	(26.8	)