Derivative Instruments and Hedging Activities (Additional Disclosures) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Collateral provided to counterparties:
Offset against derivative liabilities	$ 47	$ 51
Reflected in margin and collateral deposits	8	17
Southern California Edison \| Electric Utility \| Economic hedges
Derivatives
Realized gains (losses)	(227)	(165)	(156)
Unrealized gains (losses)	125	(768)	36
Aggregate fair value of all derivative liabilities with credit-risk-related contingent features	6	25
Collateral already posted, fair value	0	0
Potential additional collateral	6
Potential payment of outstanding payables	$ 23

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Realized gains and losses on hedging activities, which are recognized as purchased-power expense. Because the entity recovers these costs from rate payers, earnings are not affected, but cash flows may be temporarily affected.

+ References

No definition available.

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The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

The aggregate fair value of assets needed to immediately settle the derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

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The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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The amount of the right to reclaim cash collateral under master netting arrangements that have not been offset against net derivative instrument positions.

+ References

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The amount as of the balance sheet date of the fair value of derivative liabilities that in accordance with the entity's accounting policy were offset against the right to reclaim cash collateral under a master netting arrangement.

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The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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