FAIR VALUE MEASUREMENTS 4 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 47	$ 13	$ 61	$ 23
Realized and unrealized gains (losses)	1	16	(2)	23
Allocated transmission instruments	15	17	15	18
Settlements	(6)	(23)	(17)	(41)
Balance at end of period	57	23	57	23
Change in unrealized gains (losses) relating to instruments still held at period end	2	0	1	0
CRR Auction Rate Per MWh, Minimum	(8)	(3)	(8)	(3)
CRR Auction Rate Per MWh, Maximum	$ 8	$ 5	$ 8	$ 5

CRR auction rate per MWh, maximum.

No definition available.

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- Definition

CRR auction rate per MWh, minimum.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Change in unrealized gains (losses) relating to instruments still held at period end.

+ References

No definition available.

+ Details

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- Definition

No authoritative reference available.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

+ References

+ Details

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- Definition

Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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