Fair Value Measurements (Fair Value by Level) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Assets and Liabilities at Fair Values
Money market funds	$ 35		$ 68
Assets at fair value
Nuclear decommissioning trusts	4,799		4,494
Level 1
Assets and Liabilities at Fair Values
Money market funds	35		68
Southern California Edison
Assets and Liabilities at Fair Values
Money market funds	5		8
Assets at fair value
Nuclear decommissioning trusts	4,799		4,494		4,048	3,592
Liabilities at fair value
Percentage of equity investments located in the United States (as a percent)	73.00%		70.00%
Collateralized mortgage obligations and other asset backed securities	49		47
Receivables (payables) net related to investments	(57)		12
Southern California Edison | Stocks
Assets at fair value
Nuclear decommissioning trusts	2,031		2,208
Southern California Edison | Fair Value, Measurements, Recurring | Level 1
Assets at fair value
Derivative contracts	0		0
Other	33		39
Nuclear decommissioning trusts	3,340	[1]	3,380	[1]
Total assets	3,373		3,419
Liabilities at fair value
Derivative contracts	0		0
Total liabilities	0		0
Net assets (liabilities)	3,373		3,419
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Stocks
Assets at fair value
Nuclear decommissioning trusts	2,031	[2]	2,208	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Level 1 | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	703	[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	606		331
Southern California Edison | Fair Value, Measurements, Recurring | Level 2
Assets at fair value
Derivative contracts	0		11
Other	0		0
Nuclear decommissioning trusts	1,516	[1]	1,102	[1]
Total assets	1,516		1,113
Liabilities at fair value
Derivative contracts	86		37
Total liabilities	86		37
Net assets (liabilities)	1,430		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	1,350	[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	166		0
Southern California Edison | Fair Value, Measurements, Recurring | Level 3
Assets at fair value
Derivative contracts	321		372
Other	0		0
Nuclear decommissioning trusts	0	[1]	0	[1]
Total assets	321		372
Liabilities at fair value
Derivative contracts	1,223		1,177
Total liabilities	1,223		1,177
Net assets (liabilities)	(902)		(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 | Gross amounts offset in consolidated balance sheets
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	(61)	[4]	(20)	[4]
Total liabilities	(61)	[4]	(20)	[4]
Net assets (liabilities)	61	[4]	10	[4]
Southern California Edison | Fair Value, Measurements, Recurring | Gross amounts offset in consolidated balance sheets | Stocks
Assets at fair value
Nuclear decommissioning trusts	0	[2],[4]	0	[2],[4]
Southern California Edison | Fair Value, Measurements, Recurring | Gross amounts offset in consolidated balance sheets | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	0	[3],[4]	0	[3],[4]
Southern California Edison | Fair Value, Measurements, Recurring | Gross amounts offset in consolidated balance sheets | 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	321		373
Other	33		39
Nuclear decommissioning trusts	4,856	[1]	4,482	[1]
Total assets	5,210		4,894
Liabilities at fair value
Derivative contracts	1,248		1,194
Total liabilities	1,248		1,194
Net assets (liabilities)	3,962		3,700
Southern California Edison | Fair Value, Measurements, Recurring | Total | Stocks
Assets at fair value
Nuclear decommissioning trusts	2,031	[2]	2,208	[2]
Southern California Edison | Fair Value, Measurements, Recurring | Total | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	2,053	[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	$ 772		$ 331

[1] Excludes net payables of $57 million at December 31, 2014 and net receivables of $12 million at 2013, which consist of interest and dividend receivables as well as receivables and payables related to SCE's pending securities sales and purchases.

[2] Approximately 73% and 70% of SCE's equity investments were located in the United States at December 31, 2014 and 2013, respectively.

[3] Includes corporate bonds, which were diversified and included collateralized mortgage obligations and other asset backed securities of $49 million and $47 million at December 31, 2014 and 2013, 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.