Fair Value Measurements (Level 3 Rollforward) (Details) - Southern California Edison - Level 3 - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net liabilities at beginning of period		$ (902)	$ (805)
Total realized/unrealized gains (losses):
Included in regulatory assets and liabilities	[1]	(246)	(97)
Purchases		0	27
Settlements		0	(27)
Fair value of net liabilities at end of period		(1,148)	(902)
Change during the period in unrealized gains and losses related to assets and liabilities held at the end of the period		$ (311)	$ (166)

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