SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR DECOMMISSIONING TRUSTS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Cost	$ 728		$ 728		$ 731
Gross unrealized gains	331		331		259
Gross unrealized losses	(10)		(10)		(16)
Estimated fair value	1,049		1,049		974
Proceeds from sales	231	$ 216	728	$ 703
Gross realized gains	5	3	18	32
Gross realized losses	(1)	$ (1)	(4)	$ (6)
Total debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	557		557		556
Gross unrealized gains	22		22		6
Gross unrealized losses	(1)		(1)		(6)
Estimated fair value	578		578		556
U.S. government corporations and agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	51		51		52
Gross unrealized gains	0		0		1
Gross unrealized losses	0		0		0
Estimated fair value	51		51		53
Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	278		278		266
Gross unrealized gains	13		13		4
Gross unrealized losses	0		0		(1)
Estimated fair value	291		291		269
Other securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	228		228		238
Gross unrealized gains	9		9		1
Gross unrealized losses	(1)		(1)		(5)
Estimated fair value	236		236		234
Equity securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	170		170		168
Gross unrealized gains	309		309		253
Gross unrealized losses	(9)		(9)		(10)
Estimated fair value	470		470		411
Cash and cash equivalents [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	1		1		7
Gross unrealized gains	0		0		0
Gross unrealized losses	0		0		0
Estimated fair value	$ 1		$ 1		$ 7