Fair Value Measurements (Fair Value by Level) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Mar. 31, 2014	Dec. 31, 2013		Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Assets at Fair Value
Nuclear decommissioning trusts	$ 4,740			$ 4,494
Liabilities at Fair Value
Money market funds	63			68
Southern California Edison
Assets at Fair Value
Nuclear decommissioning trusts	4,740		4,587	4,494		4,181	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	61			47
Receivables (payables) net related to investments	(20)			12
Money market funds	5			8
Southern California Edison | Fair Value, Measurements, Recurring | Level 1
Assets at Fair Value
Derivative contracts	0			0
Other	32			39
Nuclear decommissioning trusts	3,362	[1]		3,380	[1]
Total assets	3,394			3,419
Liabilities at Fair Value
Derivative contracts	0			0
Total liabilities	0			0
Net assets (liabilities)	3,394			3,419
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,332	[2]		2,208	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	710	[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	320			331
Southern California Edison | Fair Value, Measurements, Recurring | Level 2
Assets at Fair Value
Derivative contracts	0			11
Other	0			0
Nuclear decommissioning trusts	1,398	[1]		1,102	[1]
Total assets	1,398			1,113
Liabilities at Fair Value
Derivative contracts	14			37
Total liabilities	14			37
Net assets (liabilities)	1,384			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	1,373	[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	25			0
Southern California Edison | Fair Value, Measurements, Recurring | Level 3
Assets at Fair Value
Derivative contracts	310			372
Other	0			0
Nuclear decommissioning trusts	0	[1]		0	[1]
Total assets	310			372
Liabilities at Fair Value
Derivative contracts	1,188			1,177
Total liabilities	1,188			1,177
Net assets (liabilities)	(878)			(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	0	[4]		(10)	[4]
Other	0	[4]		0	[4]
Nuclear decommissioning trusts	0	[1],[4]		0	[1],[4]
Total assets	0	[4]		(10)	[4]
Liabilities at Fair Value
Derivative contracts	(7)	[4]		(20)	[4]
Total liabilities	(7)	[4]		(20)	[4]
Net assets (liabilities)	7	[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	310			373
Other	32			39
Nuclear decommissioning trusts	4,760	[1]		4,482	[1]
Total assets	5,102			4,894
Liabilities at Fair Value
Derivative contracts	1,195			1,194
Total liabilities	1,195			1,194
Net assets (liabilities)	3,907			3,700
Southern California Edison | Fair Value, Measurements, Recurring | Total | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,332	[2]		2,208	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Total | Fixed income
Assets at Fair Value
Nuclear decommissioning trusts	2,083	[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	$ 345			$ 331

[1] Excludes net payables of $20 million and net receivables of $12 million at June 30, 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 both June 30, 2014 and December 31, 2013.

[3] At June 30, 2014 and December 31, 2013, SCE's corporate bonds were diversified and included collateralized mortgage obligations and other asset backed securities of $61 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.