SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR DECOMMISSIONING TRUSTS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cost	$ 734		$ 734		$ 731
Gross unrealized gains	292		292		290
Gross unrealized losses	(2)		(2)		(2)
Estimated fair value	1,024		1,024		1,019
Proceeds from sales	254	$ 245	542	$ 797
Gross realized gains	18	7	39	99
Gross realized losses	(1)	$ (6)	(3)	$ (11)
Total debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	626		626		625
Gross unrealized gains	28		28		36
Gross unrealized losses	(1)		(1)		0
Estimated fair value	653		653		661
U.S. government corporations and agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	61		61		64
Gross unrealized gains	0		0		1
Gross unrealized losses	0		0		0
Estimated fair value	61		61		65
Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	308		308		308
Gross unrealized gains	16		16		18
Gross unrealized losses	0		0		0
Estimated fair value	324		324		326
Other securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	257		257		253
Gross unrealized gains	12		12		17
Gross unrealized losses	(1)		(1)		0
Estimated fair value	268		268		270
Equity securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	104		104		112
Gross unrealized gains	264		264		254
Gross unrealized losses	(1)		(1)		(2)
Estimated fair value	367		367		364
Cash and cash equivalents [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	8		8		3
Gross unrealized gains	0		0		0
Gross unrealized losses	0		0		0
Estimated fair value	8		8		3
Receivables (payables), net [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	(4)		(4)		(9)
Gross unrealized gains	0		0		0
Gross unrealized losses	0		0		0
Estimated fair value	$ (4)		$ (4)		$ (9)