Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended													3 Months Ended				9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2012 Stocks	Dec. 31, 2011 Stocks	Sep. 30, 2012 Municipal bonds	Dec. 31, 2011 Municipal bonds	Sep. 30, 2012 U.S. government and agency securities	Dec. 31, 2011 U.S. government and agency securities	Sep. 30, 2012 Corporate bonds	Dec. 31, 2011 Corporate bonds	Sep. 30, 2012 Level 3		Sep. 30, 2011 Level 3		Sep. 30, 2012 Level 3		Sep. 30, 2011 Level 3		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Electricity	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Electricity	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Natural Gas	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Natural Gas	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Fuel Oil	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Fuel Oil	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Tolling	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Tolling	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Interest rate contracts	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Interest rate contracts	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Stocks		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Stocks		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Municipal bonds	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 U.S. government and agency securities	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 U.S. government and agency securities	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Corporate bonds		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Corporate bonds		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Short-term investments, primarily cash equivalents		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Short-term investments, primarily cash equivalents	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Electricity	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Electricity	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Natural Gas	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Natural Gas	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Fuel Oil	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Fuel Oil	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Tolling	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Tolling	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Interest rate contracts	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Interest rate contracts	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Stocks		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Stocks		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Municipal bonds	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 U.S. government and agency securities	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 U.S. government and agency securities	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Corporate bonds		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Corporate bonds		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Short-term investments, primarily cash equivalents		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Short-term investments, primarily cash equivalents	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Electricity	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Electricity	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Natural Gas	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Natural Gas	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Fuel Oil	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Fuel Oil	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Tolling	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Tolling	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Interest rate contracts	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Interest rate contracts	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Stocks		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Stocks		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Municipal bonds	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 U.S. government and agency securities	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 U.S. government and agency securities	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Corporate bonds		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Corporate bonds		Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Short-term investments, primarily cash equivalents		Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Short-term investments, primarily cash equivalents	Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Electricity		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Electricity		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Natural Gas		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Natural Gas		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Fuel Oil		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Fuel Oil		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Tolling		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Tolling		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Interest rate contracts		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Interest rate contracts		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Stocks		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Stocks		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Municipal bonds		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Municipal bonds		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral U.S. government and agency securities		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral U.S. government and agency securities		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Corporate bonds		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Corporate bonds		Sep. 30, 2012 Fair Value, Measurements, Recurring Netting and Collateral Short-term investments, primarily cash equivalents		Dec. 31, 2011 Fair Value, Measurements, Recurring Netting and Collateral Short-term investments, primarily cash equivalents		Sep. 30, 2012 Fair Value, Measurements, Recurring Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Total		Sep. 30, 2012 Fair Value, Measurements, Recurring Total Electricity	Dec. 31, 2011 Fair Value, Measurements, Recurring Total Electricity	Sep. 30, 2012 Fair Value, Measurements, Recurring Total Natural Gas	Dec. 31, 2011 Fair Value, Measurements, Recurring Total Natural Gas	Sep. 30, 2012 Fair Value, Measurements, Recurring Total Fuel Oil	Dec. 31, 2011 Fair Value, Measurements, Recurring Total Fuel Oil	Sep. 30, 2012 Fair Value, Measurements, Recurring Total Tolling	Dec. 31, 2011 Fair Value, Measurements, Recurring Total Tolling	Sep. 30, 2012 Fair Value, Measurements, Recurring Total Interest rate contracts	Dec. 31, 2011 Fair Value, Measurements, Recurring Total Interest rate contracts	Sep. 30, 2012 Fair Value, Measurements, Recurring Total Stocks		Dec. 31, 2011 Fair Value, Measurements, Recurring Total Stocks		Sep. 30, 2012 Fair Value, Measurements, Recurring Total Municipal bonds	Dec. 31, 2011 Fair Value, Measurements, Recurring Total Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring Total U.S. government and agency securities	Dec. 31, 2011 Fair Value, Measurements, Recurring Total U.S. government and agency securities	Sep. 30, 2012 Fair Value, Measurements, Recurring Total Corporate bonds		Dec. 31, 2011 Fair Value, Measurements, Recurring Total Corporate bonds		Sep. 30, 2012 Fair Value, Measurements, Recurring Total Short-term investments, primarily cash equivalents		Dec. 31, 2011 Fair Value, Measurements, Recurring Total Short-term investments, primarily cash equivalents
Assets at Fair Value
Money market funds	$ 933			$ 1,300																			$ 933	[1]	$ 1,293	[1]																										$ 0	[1]	$ 0	[1]																										$ 0	[1]	$ 0	[1]																										$ 0	[1],[2]	$ 0	[1],[2]																																									$ 933	[1]	$ 1,293	[1]
Derivative contracts																							3		8		0	0	1	4	2	4	0	0																		85		70		85	65	0	5	0	0	0	0																		152		228		148	218	0	0	0	0	4	10																		(47)	[2]	(69)	[2]	(44)	[2]	(58)	[2]	(1)	[2]	(7)	[2]	(2)	[2]	(4)	[2]	0	[2]	0	[2]																									193		237		189	225	0	2	0	0	4	10
Long-term disability plan																							8		8																											0		0																											0		0																											0	[2]	0	[2]																																									8		8
Nuclear decommissioning trusts	3,997	3,393	3,810	3,592	3,657	3,480	2,227	1,899	654	756	589	580	374	317									2,694		2,332												2,227	[3]	1,899	[3]	0	0	467	433	0	[4]	0	[4]	0	[5]	0	1,295		1,235												0	[3]	0	[3]	654	756	122	147	374	[4]	317	[4]	145	[5]	15	0		0												0	[3]	0	[3]	0	0	0	0	0	[4]	0	[4]	0	[5]	0	0	[2]	0	[2]																					0	[2],[3]	0	[2],[3]	0	[2]	0	[2]	0	[2]	0	[2]	0	[2],[4]	0	[2],[4]	0	[2],[5]	0	[2]	3,989		3,567												2,227	[3]	1,899	[3]	654	756	589	580	374	[4]	317	[4]	145	[5]	15
Total assets															152				152				3,638	[6]	3,641	[6]																										1,380	[6]	1,305	[6]																										152	[6]	228	[6]																										(47)	[2],[6]	(69)	[2],[6]																																									5,123	[6]	5,105	[6]
Liabilities at Fair Value
Derivative contracts																							1		0		0	0	1	0			0	0	0	0																123		244		8	10	115	234			0	0	125	90																640		551		17	77	6	23			617	451	0	0																(63)	[2]	(69)	[2]	(15)	[2]	(17)	[2]	(48)	[2]	(52)	[2]					0	[2]	0	[2]	0	[2]	0	[2]																					701		726		10	70	74	205			617	451	125	90
Total liabilities															640				640				1		0																											248		334																											640		551																											(63)	[2]	(69)	[2]																																									826		816
Net assets (liabilities)																							3,637		3,641																											1,132		971																											(488)		(323)																											16	[2]	0	[2]																																									4,297		4,289
Percentage of equity investments located in the United States (as a percent)	67.00%			70.00%
Collateralized mortgage obligations and other asset backed securities	42			22
Receivables (payables) net related to investments	8			25
Cash surrender value of life insurance	70			81
Leveraged leases	77			118
Fair Value Disclosures Level 3
Fair value of net asset (liabilities) at beginning of period															(343)		(275)		(323)		97
Total realized/unrealized gains (losses):
Included in earnings															12	[7]	(4)	[7]	20	[7]	14	[7]
Included in regulatory assets and liabilities															(124)	[8],[9]	162	[8],[9]	(140)	[8],[9]	(220)	[8],[9]
Included in accumulated other comprehensive income															(1)	[10]	1	[10]	1	[10]	(2)	[10]
Purchases															41		24		111		51
Settlements															(73)		(8)		(106)		(38)
Transfers into Level 3															0		0		0		0
Transfers out of Level 3															0	[11]	0	[11]	(51)	[11]	(2)	[11]
Fair value of net liabilities at end of period															(488)		(100)		(488)		(100)
Change during the period in unrealized losses related to assets and liabilities held at the end of the period															(173)	[12]	(110)	[12]	(181)	[12]	(425)	[12]
Unrealized gain (loss) related to Level 3 financial instruments reported within competitive power generation revenue	$ (7)	$ 7

[1] Money market funds are included in cash and cash equivalents and restricted cash and cash equivalents on Edison International's consolidated balance sheets.

[2] Represents the netting of assets and liabilities under master netting agreements and cash collateral across the levels of the fair value hierarchy. Netting among positions classified within the same level is included in that level.

[3] Approximately 67% and 70% of the equity investments were located in the United States at September 30, 2012 and December 31, 2011, respectively.

[4] At September 30, 2012 and December 31, 2011, corporate bonds were diversified and included collateralized mortgage obligations and other asset backed securities of $42 million and $22 million, respectively.

[5] Excludes net receivables of $8 million and $25 million at September 30, 2012 and December 31, 2011, respectively, of interest and dividend receivables as well as receivables and payables related to pending securities sales and purchases.

[6] Excludes other investments of $70 million and $81 million at September 30, 2012 and December 31, 2011, respectively, primarily related to the cash surrender value of company owned life insurance investments which are used to fund certain executive benefits including deferred compensation. Also excludes other investments of $77 million and $118 million at September 30, 2012 and December 31, 2011, respectively, primarily related to leveraged leases.

[7] Reported in "Competitive power generation" revenue on Edison International's consolidated statements of income.

[8] Includes the elimination of the fair value of derivatives with SCE's consolidated affiliates.

[9] Due to regulatory mechanisms, SCE's realized and unrealized gains and losses are recorded as regulatory assets and liabilities.

[10] Included in reclassification adjustments in Edison International's consolidated statements of other comprehensive income.

[11] Transfers out of Level 3 into Level 2 occurred due to significant observable inputs becoming available as the transactions near maturity.

[12] Amounts reported in "Competitive power generation" revenue on Edison International's consolidated statements of income was a loss of $7 million for three months ended September 30, 2012, and a gain of $7 million for the nine months ended September 30, 2011. The remainder of the unrealized losses relate to SCE. See 2 above.