Fair Value Measurements (Level 3 Rollforward) (Details) - Southern California Edison - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net assets at beginning of period	$ 34	$ 63	$ 78	$ 141
Total realized/unrealized losses	(6)	0	(50)	(78)
Fair value of net assets at end of period	28	63	28	63
Change during the period in unrealized gains and losses related to assets and liabilities held at the end of the period	$ 13	$ 30	$ 8	$ 27