Variable Interest Entities (Summary of Trusts' Income Statement) (Details) - VIE - Southern California Edison - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Trust II
Variable Interest Entity
Dividend income	$ 5	$ 5
Dividend distributions	5	5
Trust III
Variable Interest Entity
Dividend income	4	4
Dividend distributions	4	4
Trust IV
Variable Interest Entity
Dividend income	4	4
Dividend distributions	4	4
Trust V
Variable Interest Entity
Dividend income	4	4
Dividend distributions	4	4
Trust VI
Variable Interest Entity
Dividend income	6	6
Dividend distributions	$ 6	$ 6