SAN ONOFRE NUCLEAR GENERATING STATION - NUCLEAR DECOMMISSIONING TRUSTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cost	$ 735	$ 731	$ 729
Gross unrealized gains	282	290	360
Gross unrealized losses	(5)	(2)	(7)
Estimated fair value	1,012	1,019	1,082
Proceeds from sales	961	1,439	914
Gross realized gains	67	156	24
Gross realized losses	(5)	(17)	(5)
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Cost	56	64	57
Gross unrealized gains	0	1	0
Gross unrealized losses	0	0	0
Estimated fair value	56	65	57
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Cost	309	308	270
Gross unrealized gains	13	18	12
Gross unrealized losses	(1)	0	0
Estimated fair value	321	326	282
Other securities
Debt Securities, Available-for-sale [Line Items]
Cost	255	253	218
Gross unrealized gains	7	17	9
Gross unrealized losses	(2)	0	(1)
Estimated fair value	260	270	226
Debt Securities
Debt Securities, Available-for-sale [Line Items]
Cost	620	625	545
Gross unrealized gains	20	36	21
Gross unrealized losses	(3)	0	(1)
Estimated fair value	637	661	565
Equity securities
Debt Securities, Available-for-sale [Line Items]
Cost	104	112	176
Gross unrealized gains	262	254	339
Gross unrealized losses	(2)	(2)	(6)
Estimated fair value	364	364	509
Cash and cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cost	3	3	16
Gross unrealized gains	0	0	0
Gross unrealized losses	0	0	0
Estimated fair value	3	3	16
Accounts Payable
Debt Securities, Available-for-sale [Line Items]
Cost	8	(9)	(8)
Gross unrealized gains	0	0	0
Gross unrealized losses	0	0	0
Estimated fair value	$ 8	$ (9)	$ (8)