Fair Value Measurements Fair Value Measurements (Changes in Level 3 Net Derivative Assets and Liabilities) (Details) (Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Level 3
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net assets (liabilities) at beginning of period	$ (1,097)		$ (127)		$ (754)		$ 6
Total realized/unrealized gains (losses), net:
Included in regulatory assets	341	[1]	(247)	[1]	(23)	[1]	(382)	[1]
Purchases	29		16		50		17
Settlements	(12)		(1)		(12)		0
Transfers into Level 3	0		0		0		0
Transfers out of Level 3	0		0		0		0
Fair value of net liabilities at end of period	(739)		(359)		(739)		(359)
Change during the period in unrealized gains (losses) related to assets and liabilities held at the end of the period	$ 335		$ (240)		$ (8)		$ (376)

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