Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011		Mar. 31, 2012	Dec. 31, 2011		Mar. 31, 2011	Dec. 31, 2010
Assets at Fair Value
Money market funds	$ 982				$ 982					$ 1,300
Nuclear decommissioning trusts	3,810		3,657		3,810		3,657		3,853	3,592		3,619	3,480
Liabilities at Fair Value
Percentage of equity investments located in the United States (as a percent)	67.00%				67.00%					70.00%
Collateralized mortgage obligations and other asset backed securities	44				44					22
Receivables (payables) net related to investments	(17)				(17)					25
Cash surrender value of life insurance	98				98					81
Leveraged leases	110				110					118
Total realized/unrealized gains (losses):
Unrealized gain (loss) related to Level 3 financial instruments reported within competitive power generation revenue	14		14		8		8
Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,090				2,090					1,899
Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	714				714					756
U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	549				549					580
Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	382				382					317
Level 3
Assets at Fair Value
Total assets	164				164
Liabilities at Fair Value
Total liabilities	507				507
Fair Value Disclosures Level 3
Fair value of net asset (liabilities) at beginning of period	(662)		(44)		(323)		97
Total realized/unrealized gains (losses):
Included in earnings	23	[1]	18	[1]	8	[1]	18	[1]
Included in regulatory assets and liabilities	285	[2],[3]	(247)	[2]	(16)	[2],[3]	(382)	[2]
Included in accumulated other comprehensive income	0	[4]	(4)	[4]	2	[4]	(3)	[4]
Purchases	42		22		69		28
Settlements	(31)		(20)		(32)		(31)
Transfers out of Level 3	0	[5]	0	[5]	(51)	[5]	(2)	[5]
Fair value of net liabilities at end of period	(343)		(275)		(343)		(275)
Change during the period in unrealized losses related to assets and liabilities held at the end of the period	293	[6]	(226)	[6]	7	[6]	(368)	[6]
Fair Value, Measurements, Recurring | Level 1
Assets at Fair Value
Money market funds	982	[7]			982	[7]				1,321	[7]
Derivative contracts	4				4					8
Long-term disability plan	8				8					8
Nuclear decommissioning trusts	2,481				2,481					2,332
Total assets	3,475	[8]			3,475	[8]				3,669	[8]
Liabilities at Fair Value
Derivative contracts	0				0					0
Total liabilities	0				0					0
Net assets (liabilities)	3,475				3,475					3,669
Fair Value, Measurements, Recurring | Level 1 | Electricity
Assets at Fair Value
Derivative contracts	0				0					0
Liabilities at Fair Value
Derivative contracts	0				0					0
Fair Value, Measurements, Recurring | Level 1 | Natural Gas
Assets at Fair Value
Derivative contracts	4				4					4
Liabilities at Fair Value
Derivative contracts	0				0					0
Fair Value, Measurements, Recurring | Level 1 | Fuel Oil
Assets at Fair Value
Derivative contracts										4
Fair Value, Measurements, Recurring | Level 1 | Tolling
Assets at Fair Value
Derivative contracts										0
Liabilities at Fair Value
Derivative contracts	0				0					0
Fair Value, Measurements, Recurring | Level 1 | Interest rate contracts
Liabilities at Fair Value
Derivative contracts	0				0					0
Fair Value, Measurements, Recurring | Level 1 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,090	[9]			2,090	[9]				1,899	[9]
Fair Value, Measurements, Recurring | Level 1 | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	0				0					0
Fair Value, Measurements, Recurring | Level 1 | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	389				389					433
Fair Value, Measurements, Recurring | Level 1 | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[10]			0	[10]				0	[10]
Fair Value, Measurements, Recurring | Level 1 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	2	[11]			2	[11]				0	[11]
Fair Value, Measurements, Recurring | Level 2
Assets at Fair Value
Money market funds	0	[7]			0	[7]				0	[7]
Derivative contracts	108				108					71
Long-term disability plan	0				0					0
Nuclear decommissioning trusts	1,346				1,346					1,235
Total assets	1,454	[8]			1,454	[8]				1,306	[8]
Liabilities at Fair Value
Derivative contracts	201				201					247
Total liabilities	315				315					337
Net assets (liabilities)	1,139				1,139					969
Fair Value, Measurements, Recurring | Level 2 | Electricity
Assets at Fair Value
Derivative contracts	108				108					66
Liabilities at Fair Value
Derivative contracts	7				7					13
Fair Value, Measurements, Recurring | Level 2 | Natural Gas
Assets at Fair Value
Derivative contracts	0				0					5
Liabilities at Fair Value
Derivative contracts	194				194					234
Fair Value, Measurements, Recurring | Level 2 | Fuel Oil
Assets at Fair Value
Derivative contracts										0
Fair Value, Measurements, Recurring | Level 2 | Tolling
Assets at Fair Value
Derivative contracts										0
Liabilities at Fair Value
Derivative contracts	0				0					0
Fair Value, Measurements, Recurring | Level 2 | Interest rate contracts
Liabilities at Fair Value
Derivative contracts	114				114					90
Fair Value, Measurements, Recurring | Level 2 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[9]			0	[9]				0	[9]
Fair Value, Measurements, Recurring | Level 2 | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	714				714					756
Fair Value, Measurements, Recurring | Level 2 | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	160				160					147
Fair Value, Measurements, Recurring | Level 2 | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	382	[10]			382	[10]				317	[10]
Fair Value, Measurements, Recurring | Level 2 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	90	[11]			90	[11]				15	[11]
Fair Value, Measurements, Recurring | Level 3
Assets at Fair Value
Money market funds	0	[7]			0	[7]				0	[7]
Derivative contracts	164				164					228
Long-term disability plan	0				0					0
Nuclear decommissioning trusts	0				0					0
Total assets	164	[8]			164	[8]				228	[8]
Liabilities at Fair Value
Derivative contracts	507				507					551
Total liabilities	507				507					551
Net assets (liabilities)	(343)				(343)					(323)
Fair Value, Measurements, Recurring | Level 3 | Electricity
Assets at Fair Value
Derivative contracts	164				164					218
Liabilities at Fair Value
Derivative contracts	31				31					77
Fair Value, Measurements, Recurring | Level 3 | Natural Gas
Assets at Fair Value
Derivative contracts	0				0					0
Liabilities at Fair Value
Derivative contracts	28				28					23
Fair Value, Measurements, Recurring | Level 3 | Fuel Oil
Assets at Fair Value
Derivative contracts										0
Fair Value, Measurements, Recurring | Level 3 | Tolling
Assets at Fair Value
Derivative contracts										10
Liabilities at Fair Value
Derivative contracts	448				448					451
Fair Value, Measurements, Recurring | Level 3 | Interest rate contracts
Liabilities at Fair Value
Derivative contracts	0				0					0
Fair Value, Measurements, Recurring | Level 3 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[9]			0	[9]				0	[9]
Fair Value, Measurements, Recurring | Level 3 | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	0				0					0
Fair Value, Measurements, Recurring | Level 3 | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	0				0					0
Fair Value, Measurements, Recurring | Level 3 | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[10]			0	[10]				0	[10]
Fair Value, Measurements, Recurring | Level 3 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	0	[11]			0	[11]				0	[11]
Fair Value, Measurements, Recurring | Netting and Collateral
Assets at Fair Value
Money market funds	0	[12],[7]			0	[12],[7]				0	[12],[7]
Derivative contracts	(74)	[12]			(74)	[12]				(73)	[12]
Long-term disability plan	0	[12]			0	[12]				0	[12]
Nuclear decommissioning trusts	0	[12]			0	[12]				0	[12]
Total assets	(74)	[12],[8]			(74)	[12],[8]				(73)	[12],[8]
Liabilities at Fair Value
Derivative contracts	(94)	[12]			(94)	[12]				(73)	[12]
Total liabilities	(94)	[12]			(94)	[12]				(73)	[12]
Net assets (liabilities)	20	[12]			20	[12]				0	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Electricity
Assets at Fair Value
Derivative contracts	(70)	[12]			(70)	[12]				(62)	[12]
Liabilities at Fair Value
Derivative contracts	(28)	[12]			(28)	[12]				(21)	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Natural Gas
Assets at Fair Value
Derivative contracts	(4)	[12]			(4)	[12]				(7)	[12]
Liabilities at Fair Value
Derivative contracts	(66)	[12]			(66)	[12]				(52)	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Fuel Oil
Assets at Fair Value
Derivative contracts										(4)	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Tolling
Assets at Fair Value
Derivative contracts										0	[12]
Liabilities at Fair Value
Derivative contracts	0	[12]			0	[12]				0	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Interest rate contracts
Liabilities at Fair Value
Derivative contracts	0	[12]			0	[12]				0	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[12],[9]			0	[12],[9]				0	[12],[9]
Fair Value, Measurements, Recurring | Netting and Collateral | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[12]			0	[12]				0	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	0	[12]			0	[12]				0	[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[10],[12]			0	[10],[12]				0	[10],[12]
Fair Value, Measurements, Recurring | Netting and Collateral | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	0	[11],[12]			0	[11],[12]				0	[11],[12]
Fair Value, Measurements, Recurring | Total
Assets at Fair Value
Money market funds	982	[7]			982	[7]				1,321	[7]
Derivative contracts	202				202					234
Long-term disability plan	8				8					8
Nuclear decommissioning trusts	3,827				3,827					3,567
Total assets	5,019	[8]			5,019	[8]				5,130	[8]
Liabilities at Fair Value
Derivative contracts	614				614					725
Total liabilities	728				728					815
Net assets (liabilities)	4,291				4,291					4,315
Fair Value, Measurements, Recurring | Total | Electricity
Assets at Fair Value
Derivative contracts	202				202					222
Liabilities at Fair Value
Derivative contracts	10				10					69
Fair Value, Measurements, Recurring | Total | Natural Gas
Assets at Fair Value
Derivative contracts	0				0					2
Liabilities at Fair Value
Derivative contracts	156				156					205
Fair Value, Measurements, Recurring | Total | Fuel Oil
Assets at Fair Value
Derivative contracts										0
Fair Value, Measurements, Recurring | Total | Tolling
Assets at Fair Value
Derivative contracts										10
Liabilities at Fair Value
Derivative contracts	448				448					451
Fair Value, Measurements, Recurring | Total | Interest rate contracts
Liabilities at Fair Value
Derivative contracts	114				114					90
Fair Value, Measurements, Recurring | Total | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,090	[9]			2,090	[9]				1,899	[9]
Fair Value, Measurements, Recurring | Total | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	714				714					756
Fair Value, Measurements, Recurring | Total | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	549				549					580
Fair Value, Measurements, Recurring | Total | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	382	[10]			382	[10]				317	[10]
Fair Value, Measurements, Recurring | Total | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	$ 92	[11]			$ 92	[11]				$ 15	[11]

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

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

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

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

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

[6] Amounts reported in "Competitive power generation" revenue on Edison International's consolidated statements of income were $14 million and for both the three months ended June 30, 2012 and 2011, and were $8 million for both the six months ended June 30, 2012 and 2011. The remainder of the unrealized losses relate to SCE. See 2 above.

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

[8] Excludes other investments of $98 million and $81 million at June 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 $110 million and $118 million at June 30, 2012 and December 31, 2011, respectively, primarily related to leveraged leases.

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

[10] At June 30, 2012 and December 31, 2011, corporate bonds were diversified and included collateralized mortgage obligations and other asset backed securities of $44 million and $22 million, respectively.

[11] Excludes net payables of $17 million and net receivables of $25 million at June 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.

[12] 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.