Fair Value (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Disclosures [Abstract]

Assets and liabilities measured and recorded at fair value on a recurring basis [Table Text Block]

	December 31, 2012								December 31, 2011
	Level 1		Level 2		Level 3		Net Balance		Level 1		Level 2		Level 3		Net Balance
	(In millions)
Assets:
Cash equivalents (a)	$	—	$	116	$	—	$	116	$	—	$	129	$	—	$	129
Nuclear decommissioning trusts	694		343		—		1,037		577		360		—		937
Other investments (b)	64		44		—		108		55		38		—		93
Derivative assets — FTRs	—		—		1		1		—		—		1		1
Total	$	758	$	503	$	1	$	1,262	$	632	$	527	$	1	$	1,160
Assets:
Current	$	—	$	116	$	1	$	117	$	—	$	129	$	1	$	130
Noncurrent	758		387		—		1,145		632		398		—		1,030
Total Assets	$	758	$	503	$	1	$	1,262	$	632	$	527	$	1	$	1,160

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

The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2012 and 2011:

	Year Ended December 31
	2012			2011
	(In millions)
Net Assets as of January 1	$	1		2
Change in fair value recorded in regulatory assets/liabilities	15			2
Purchases, issuances and settlements:
Settlements	(15		)	(3		)
Net Assets as of December 31	$	1		$	1
The amount of total gains (losses) included in regulatory assets and liabilities attributed to the change in unrealized gains (losses) related to regulatory assets and liabilities held at December 31, 2012 and 2011	$	1		$	1

Fair Value of Financial Instruments [Table Text Block]

The following table presents the carrying amount and fair value of financial instruments as of December 31, 2012 and December 31, 2011:

	December 31, 2012								December 31, 2011
	Carrying		Fair Value						Carrying		Fair
	Amount		Level 1		Level 2		Level 3		Amount		Value
	(In millions)
Notes receivable, excluding capital leases	$	5	$	—	$	—	$	5	$	6	$	6
Notes receivable — affiliates	—		—		—		—		26		26
Short-term borrowings — affiliates	80		—		—		80		64		64
Short-term borrowings — other	130		—		130		—		—		—
Long-term debt	4,963		—		5,021		620		5,051		5,740

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

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

	December 31		December 31
	2012		2011
	(In millions)
Fermi 2	$	1,021	$	915
Fermi 1	3		3
Low level radioactive waste	13		19
Total	$	1,037	$	937

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:

	Year Ended December 31
	2012			2011			2010
	(In millions)
Realized gains	$	37		$	46		$	192
Realized losses	$	(31	)	$	(38	)	$	(83	)
Proceeds from sales of securities	$	97		$	80		$	377

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

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

	December 31, 2012				December 31, 2011
	Fair		Unrealized		Fair		Unrealized
	Value		Gains		Value		Gains
	(In millions)
Equity securities	$	631	$	122	$	533	$	80
Debt securities	399		27		385		22
Cash and cash equivalents	7		—		19		—
	$	1,037	$	149	$	937	$	102