SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR DECOMMISSIONING TRUSTS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cost	$ 728		$ 728		$ 731
Gross unrealized gains	279		279		290
Gross unrealized losses	(4)		(4)		(2)
Estimated fair value	1,003		1,003		1,019
Proceeds from sales	187	$ 294	729	$ 1,091
Gross realized gains	9	9	48	108
Gross realized losses	(1)	$ (2)	(4)	$ (13)
Total debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	620		620		625
Gross unrealized gains	24		24		36
Gross unrealized losses	(2)		(2)		0
Estimated fair value	642		642		661
U.S. government corporations and agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	52		52		64
Gross unrealized gains	0		0		1
Gross unrealized losses	0		0		0
Estimated fair value	52		52		65
Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	307		307		308
Gross unrealized gains	14		14		18
Gross unrealized losses	(1)		(1)		0
Estimated fair value	320		320		326
Other securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	261		261		253
Gross unrealized gains	10		10		17
Gross unrealized losses	(1)		(1)		0
Estimated fair value	270		270		270
Equity securities [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	103		103		112
Gross unrealized gains	255		255		254
Gross unrealized losses	(2)		(2)		(2)
Estimated fair value	356		356		364
Cash and cash equivalents [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	7		7		3
Gross unrealized gains	0		0		0
Gross unrealized losses	0		0		0
Estimated fair value	7		7		3
Receivables (payables), net [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	(2)		(2)		(9)
Gross unrealized gains	0		0		0
Gross unrealized losses	0		0		0
Estimated fair value	$ (2)		$ (2)		$ (9)