Related Party Transactions (Summary of Related Party Transactions) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Related Party Transaction [Line Items]
Total receivables due from unconsolidated affiliates	$ 207
Total payables due to unconsolidated affiliates	161
Affiliates
Related Party Transaction [Line Items]
Long-term payables due to related party	36
Edison Mission Energy
Related Party Transaction [Line Items]
Current receivables due from related party	2
Long-term income tax receivables due from related party	205	[1]
Current payables due to related party	11
Current income taxes payable to related party	99
Long-term payables due to related party	15
Joint tax liability	183
Southern California Edison
Related Party Transaction [Line Items]
Total receivables due from unconsolidated affiliates	13		24
Total payables due to unconsolidated affiliates	129		8
Southern California Edison | Affiliates
Related Party Transaction [Line Items]
Current receivables due from related party	12		23
Current payables due to related party	7		8
Southern California Edison | Edison International
Related Party Transaction [Line Items]
Long-term income tax receivables due from related party	1		1
Long-term payables due to related party	$ 122	[2]	$ 0	[2]

[1] Edison International Parent has recorded liabilities at December 31, 2012 of $183 million related to joint tax liabilities with EME. Under the tax allocation agreements, EME is obligated for such liabilities and, accordingly, Edison International has recorded a receivable from EME in this amount. See Note 18 for further information.

[2] Relates to certain SCE postretirement benefits transferred to Edison International Parent. See Note 8 for further information.