Fair Value (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value - (Tables) [Abstract]

Fair Value Measurements of Energy Commodity Derivative Contracts and Interest Rate Swap Agreement Assets Table

	Asset fair value measurements using
	Total		Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
As of September 30, 2011
Energy commodity derivative contracts(a)	$	262.1	$	25.3	$	172.2	$	64.6
Interest rate swap agreements	$	576.5	$	-	$	576.5	$	-
As of December 31, 2010
Energy commodity derivative contracts(a)	$	67.1	$	-	$	23.5	$	43.6
Interest rate swap agreements	$	217.6	$	-	$	217.6	$	-

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Fair Value Measurements of Energy Commodity Derivative Contracts and Interest Rate Swap Agreement Liabilities Table

	Liability fair value measurements using
	Total			Quoted prices in active markets for identical liabilities (Level 1)			Significant other observable inputs (Level 2)			Significant unobservable inputs (Level 3)
As of September 30, 2011
Energy commodity derivative contracts(a)	$	(93.3	)	$	(12.6	)	$	(60.7	)	$	(20.0	)
Interest rate swap agreements	$	-		$	-		$	-		$	-
As of December 31, 2010
Energy commodity derivative contracts(a)	$	(384.5	)	$	-		$	(359.7	)	$	(24.8	)
Interest rate swap agreements	$	(69.2	)	$	-		$	(69.2	)	$	-

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(a) Level 1 consists primarily of NYMEX natural gas futures.  Level 2 consists primarily of OTC West Texas Intermediate swaps and OTC natural gas swaps that are settled on NYMEX.  Level 3 consists primarily of natural gas basis swaps and West Texas Intermediate options.

Significant Unobservable Inputs (Level 3) Table

Significant unobservable inputs (Level 3)
	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2010			2011			2010
Derivatives-net asset (liability)
Beginning of Period	$	6.7		$	46.6		$	18.8		$	13.0
Transfers into Level 3		-			-			-			-
Transfers out of Level 3		-			-			-			-
Total gains or (losses):
Included in earnings		2.6			(7.5	)		5.4			3.6
Included in other comprehensive income		37.0			(3.9	)		21.5			11.7
Purchases		-			-			4.6			-
Issuances		-			-			-			-
Sales		-			-			-			-
Settlements		(1.7	)		(0.6	)		(5.7	)		6.3
End of Period	$	44.6		$	34.6		$	44.6		$	34.6
The amount of total gains or (losses) for the period included   in earnings attributable to the change in unrealized gains or   (losses) relating to assets held at the reporting date	$	3.2		$	(5.8	)	$	4.4		$	1.3

Estimated Fair Value of Outstanding Debt Balance

The estimated fair value of our outstanding debt balance as of September 30, 2011 and December 31, 2010 (both short-term and long-term, but excluding the value of interest rate swaps) is disclosed below (in millions):

	September 30, 2011				December 31, 2010
	Carrying Value		Estimated Fair value		Carrying Value		Estimated fair value
Total debt	$	12,506.6	$	13,873.0	$	11,539.8	$	12,443.4