Fair Value (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value Disclosures [Abstract]

Assets and liabilities measured and recorded at fair value on a recurring basis

The following table presents assets and liabilities measured and recorded at fair value on a recurring basis as of September 30, 2011:

										Netting			Net Balance at
(in Millions)	Level 1			Level 2			Level 3			Adjustments(2)			September 30, 2011
Assets:
Nuclear decommissioning trusts	$	532		$	361		$	—		$	—		$	893
Other investments(1)	48			56			—			—			104
Derivative assets:
Foreign currency exchange contracts	—			6			—			(6		)	—
Commodity Contracts:
Natural Gas	1,650			79			17			(1,698		)	48
Electricity	—			326			67			(282		)	111
Other	22			—			7			(20		)	9
Total derivative assets	1,672			411			91			(2,006		)	168
Total	$	2,252		$	828		$	91		$	(2,006	)	$	1,165
Liabilities:
Derivative liabilities:
Foreign currency exchange contracts	$	—		$	(9	)	$	—		$	6		$	(3	)
Interest rate contracts	—			(1		)	—			—			(1		)
Commodity Contracts:
Natural Gas	(1,616		)	(167		)	(12		)	1,698			(97		)
Electricity	—			(295		)	(70		)	285			(80		)
Other	(14		)	(1		)	—			20			5
Total derivative liabilities	(1,630		)	(473		)	(82		)	2,009			(176		)
Total	$	(1,630	)	$	(473	)	$	(82	)	$	2,009		$	(176	)
Net Assets as of September 30, 2011	$	622		$	355		$	9		$	3		$	989
Assets:
Current	$	1,251		$	322		$	62		$	(1,526	)	$	109
Noncurrent(3)	1,001			506			29			(480		)	1,056
Total Assets	$	2,252		$	828		$	91		$	(2,006	)	$	1,165
Liabilities:
Current	$	(1,235	)	$	(348	)	$	(60	)	$	1,529		$	(114	)
Noncurrent	(395		)	(125		)	(22		)	480			(62		)
Total Liabilities	$	(1,630	)	$	(473	)	$	(82	)	$	2,009		$	(176	)
Net Assets as of September 30, 2011	$	622		$	355		$	9		$	3		$	989

The following table presents assets and liabilities measured and recorded at fair value on a recurring basis as of December 31, 2010:

										Netting			Net Balance at
(in Millions)	Level 1			Level 2			Level 3			Adjustments(2)			December 31, 2010
Assets:
Nuclear decommissioning trusts	$	599		$	340		$	—		$	—		$	939
Other investments(1)	56			55			—			—			111
Derivative assets:
Foreign currency exchange contracts	—			20			—			(20		)	—
Commodity Contracts:
Natural Gas	1,846			128			12			(1,960		)	26
Electricity	—			649			117			(589		)	177
Other	68			4			4			(71		)	5
Total derivative assets	1,914			801			133			(2,640		)	208
Total	$	2,569		$	1,196		$	133		$	(2,640	)	$	1,258
Liabilities:
Derivative liabilities:
Foreign currency exchange contracts	$	—		$	(30	)	$	—		$	20		$	(10	)
Interest rate contracts	—			(1		)	—			—			(1		)
Commodity Contracts:
Natural Gas	(1,844		)	(263		)	(11		)	1,955			(163		)
Electricity	—			(653		)	(63		)	643			(73		)
Other	(63		)	(8		)	—			66			(5		)
Total derivative liabilities	(1,907		)	(955		)	(74		)	2,684			(252		)
Total	$	(1,907	)	$	(955	)	$	(74	)	$	2,684		$	(252	)
Net Assets as of December 31, 2010	$	662		$	241		$	59		$	44		$	1,006
Assets:
Current	$	1,299		$	663		$	49		$	(1,880	)	$	131
Noncurrent(3)	1,270			533			84			(760		)	1,127
Total Assets	$	2,569		$	1,196		$	133		$	(2,640	)	$	1,258
Liabilities:
Current	$	(1,290	)	$	(730	)	$	(21	)	$	1,899		$	(142	)
Noncurrent	(617		)	(225		)	(53		)	785			(110		)
Total Liabilities	$	(1,907	)	$	(955	)	$	(74	)	$	2,684		$	(252	)
Net Assets as of December 31, 2010	$	662		$	241		$	59		$	44		$	1,006

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for the three and nine months ended September 30, 2011 and 2010:

	Three Months Ended September 30, 2011
(in Millions)	Natural Gas			Electricity			Other		Total
Net Assets as of July 1, 2011	$	1		$	57		$	7	$	65
Transfers into Level 3	(1		)	(6		)	—		(7		)
Transfers out of Level 3	—			(42		)	—		(42		)
Total gains or (losses):
Included in earnings	6			23			—		29
Purchases, issuances, sales and settlements:
Settlements	(1		)	(35		)	—		(36		)
Net Assets (Liabilities) as of September 30, 2011	$	5		$	(3	)	$	7	$	9
The amount of total gains (losses) included in net income attributed to the change in unrealized gains (losses) related to assets and liabilities held at September 30, 2011	$	6		$	5		$	—	$	11

	Three Months Ended September 30, 2010
(in Millions)	Natural Gas			Electricity			Other			Total
Net Assets as of July 1, 2010	$	2		$	155		$	4		$	161
Changes in fair value recorded in income	3			21			1			25
Purchases, issuances and settlements	(1		)	(29		)	(1		)	(31		)
Transfers in/out of Level 3	—			(22		)	—			(22		)
Net Assets as of September 30, 2010	$	4		$	125		$	4		$	133
The amount of total gains (losses) included in net income attributed to the change in unrealized gains (losses) related to assets and liabilities held at September 30, 2010	$	2		$	(4	)	$	1		$	(1	)

	Nine Months Ended September 30, 2011
(in Millions)	Natural Gas		Electricity			Other			Total
Net Assets as of January 1, 2011	$	1	$	54		$	4		$	59
Transfers into Level 3	—		(4		)	—			(4		)
Transfers out of Level 3	1		(25		)	—			(24		)
Total gains or (losses):
Included in earnings	3		34			2			39
Recorded in regulatory assets/liabilities	—		—			3			3
Purchases, issuances, sales and settlements:
Purchases	—		1			—			1
Settlements	—		(63		)	(2		)	(65		)
Net Assets (Liabilities) as of September 30, 2011	$	5	$	(3	)	$	7		$	9
The amount of total gains (losses) included in net income attributed to the change in unrealized gains (losses) related to assets and liabilities held at September 30, 2011	$	5	$	17		$	2		$	24

	Nine Months Ended September 30, 2010
(in Millions)	Natural Gas			Electricity			Other			Total
Net Assets as of January 1, 2010	$	2		$	19		$	3		$	24
Changes in fair value recorded in income	4			117			1			122
Changes in fair value recorded in regulatory assets/liabilities	—			—			4			4
Purchases, issuances and settlements	(6		)	(59		)	(4		)	(69		)
Transfers in/out of Level 3	4			48			—			52
Net Assets as of September 30, 2010	$	4		$	125		$	4		$	133
The amount of total gains (losses) included in net income attributed to the change in unrealized gains (losses) related to assets and liabilities held at September 30, 2010	$	(2	)	$	58		$	1		$	57

Fair Value of Long Term Debt [Table Text Block]

	September 30, 2011				December 31, 2010
(in Billions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-Term Debt	$	8.8	$	7.7	$	8.5	$	8.0

Fair Value of Nuclear Decommissioning Trust Fund Assets Text Block [Table]

The following table summarizes the fair value of the nuclear decommissioning trust fund assets:

	September 30,		December 31,
(in Millions)	2011		2010
Fermi 2	$	858	$	910
Fermi 1	3		3
Low level radioactive waste	32		26
Total	$	893	$	939

Schedule of Realized Gain (Loss) [Table Text Block]

The following table sets forth the gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds:

	Three Months Ended						Nine Months Ended
	September 30						September 30
(in Millions)	2011			2010			2011			2010
Realized gains	$	8		$	8		$	34		$	29
Realized losses	(9		)	(6		)	(26		)	(25		)
Proceeds from sales of securities	10			51			69			179

Fair Value and Unrealized Gains for Nuclear Decommissioning Trust Fund Table [Table] [Table Text Block]

The following table sets forth the fair value and unrealized gains for the nuclear decommissioning trust funds:

	Fair		Unrealized
(in Millions)	Value		Gains
As of September 30, 2011
Equity securities	$	485	$	52
Debt securities	395		22
Cash and cash equivalents	13		—
	$	893	$	74
As of December 31, 2010
Equity securities	$	572	$	77
Debt securities	361		11
Cash and cash equivalents	6		—
	$	939	$	88

Available-for-sale debt and equity securities

The following table summarizes the fair value of the Company’s investment in available-for-sale debt and equity securities, excluding nuclear decommissioning trust fund assets:

	September 30, 2011				December 31, 2010
(in Millions)	Fair Value		Carrying value		Fair Value		Carrying Value
Cash equivalents	$	85	$	85	$	133	$	133
Equity securities	5		5		6		6