Fair Value Measurements (Fair Value by Level) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012
Assets at Fair Value
Nuclear decommissioning trusts	$ 4,587		$ 4,494
Liabilities at Fair Value
Money market funds	67		68
Southern California Edison
Assets at Fair Value
Nuclear decommissioning trusts	4,587		4,494		4,246	4,048
Liabilities at Fair Value
Percentage of equity investments located in the United States (as a percent)	70.00%		70.00%
Collateralized mortgage obligations and other asset backed securities	46		47
Receivables (payables) net related to investments	(55)		12
Money market funds	6		8
Southern California Edison | Fair Value, Measurements, Recurring | Level 1
Assets at Fair Value
Derivative contracts	0		0
Other	38		39
Nuclear decommissioning trusts	3,346	[1]	3,380	[1]
Total assets	3,384		3,419
Liabilities at Fair Value
Derivative contracts	0		0
Total liabilities	0		0
Net assets (liabilities)	3,384		3,419
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,234	[2]	2,208	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	777	[3]	841	[3]
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	335		331
Southern California Edison | Fair Value, Measurements, Recurring | Level 2
Assets at Fair Value
Derivative contracts	20		11
Other	0		0
Nuclear decommissioning trusts	1,296	[1]	1,102	[1]
Total assets	1,316		1,113
Liabilities at Fair Value
Derivative contracts	29		37
Total liabilities	29		37
Net assets (liabilities)	1,287		1,076
Southern California Edison | Fair Value, Measurements, Recurring | Level 2 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[2]	0	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Level 2 | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	1,221	[3]	1,102	[3]
Southern California Edison | Fair Value, Measurements, Recurring | Level 2 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	75		0
Southern California Edison | Fair Value, Measurements, Recurring | Level 3
Assets at Fair Value
Derivative contracts	345		372
Other	0		0
Nuclear decommissioning trusts	0	[1]	0	[1]
Total assets	345		372
Liabilities at Fair Value
Derivative contracts	1,118		1,177
Total liabilities	1,118		1,177
Net assets (liabilities)	(773)		(805)
Southern California Edison | Fair Value, Measurements, Recurring | Level 3 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[2]	0	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Level 3 | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	0	[3]	0	[3]
Southern California Edison | Fair Value, Measurements, Recurring | Level 3 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	0		0
Southern California Edison | Fair Value, Measurements, Recurring | Netting and Collateral
Assets at Fair Value
Derivative contracts	(13)		(10)
Other	0	[4]	0	[4]
Nuclear decommissioning trusts	0	[1],[4]	0	[1],[4]
Total assets	(13)	[4]	(10)	[4]
Liabilities at Fair Value
Derivative contracts	(19)		(20)
Total liabilities	(19)	[4]	(20)	[4]
Net assets (liabilities)	6	[4]	10	[4]
Southern California Edison | Fair Value, Measurements, Recurring | Netting and Collateral | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[2],[4]	0	[2],[4]
Southern California Edison | Fair Value, Measurements, Recurring | Netting and Collateral | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	0	[3],[4]	0	[3],[4]
Southern California Edison | Fair Value, Measurements, Recurring | Netting and Collateral | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	0	[4]	0	[4]
Southern California Edison | Fair Value, Measurements, Recurring | Total
Assets at Fair Value
Derivative contracts	352		373
Other	38		39
Nuclear decommissioning trusts	4,642	[1]	4,482	[1]
Total assets	5,032		4,894
Liabilities at Fair Value
Derivative contracts	1,128		1,194
Total liabilities	1,128		1,194
Net assets (liabilities)	3,904		3,700
Southern California Edison | Fair Value, Measurements, Recurring | Total | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,234	[2]	2,208	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Total | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	1,998	[3]	1,943	[3]
Southern California Edison | Fair Value, Measurements, Recurring | Total | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	$ 410		$ 331

[1] Excludes net payables of $55 million and net receivables of $12 million at March 31, 2014 and December 31, 2013, respectively, of interest and dividend receivables as well as receivables and payables related to SCE's pending securities sales and purchases.

[2] Approximately 70% of SCE's equity investments were located in the United States at March 31, 2014 and December 31, 2013, respectively.

[3] At March 31, 2014 and December 31, 2013, SCE's corporate bonds were diversified and included collateralized mortgage obligations and other asset backed securities of $46 million and $47 million, respectively.

[4] 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.