SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR DECOMMISSIONING TRUSTS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Cost	$ 724		$ 724		$ 731
Gross unrealized gains	328		328		259
Gross unrealized losses	(8)		(8)		(16)
Estimated fair value	1,044		1,044		974
Proceeds from sales	272	$ 277	497	$ 487
Gross realized gains	8	25	13	29
Gross realized losses	(1)	$ (2)	(3)	$ (5)
Total debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	554		554		556
Gross unrealized gains	18		18		6
Gross unrealized losses	(1)		(1)		(6)
Estimated fair value	571		571		556
U.S. government corporations and agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	46		46		52
Gross unrealized gains	0		0		1
Gross unrealized losses	0		0		0
Estimated fair value	46		46		53
Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	278		278		266
Gross unrealized gains	11		11		4
Gross unrealized losses	0		0		(1)
Estimated fair value	289		289		269
Other securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	230		230		238
Gross unrealized gains	7		7		1
Gross unrealized losses	(1)		(1)		(5)
Estimated fair value	236		236		234
Equity securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	164		164		168
Gross unrealized gains	310		310		253
Gross unrealized losses	(7)		(7)		(10)
Estimated fair value	467		467		411
Cash and cash equivalents [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	6		6		7
Gross unrealized gains	0		0		0
Gross unrealized losses	0		0		0
Estimated fair value	$ 6		$ 6		$ 7