FAIR VALUE MEASUREMENTS - RECON OF LEVEL 3 ASSETS (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 16,000,000	$ 182,000,000	$ 28,000,000	$ 179,000,000	$ 179,000,000
Realized and unrealized (losses) gains	(9,000,000)	(13,000,000)	(14,000,000)	(8,000,000)
Allocated transmission instruments	1,000,000	0	1,000,000	0
Settlements	9,000,000	7,000,000	2,000,000	5,000,000
Ending balance	17,000,000	176,000,000	17,000,000	176,000,000	28,000,000
Change in unrealized gains (losses) relating to instruments still held at the end of the period	(5,000,000)	(3,000,000)	(13,000,000)	9,000,000
Level 3 [Member] | San Diego Gas and Electric Company [Member] | Minimum [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Congestion revenue rights (in dollars per MWH)			(3.77)		(8.57)
Market electricity forward price inputs ( in dollars per MWH)	20.35	22.00	20.35	22.00
Level 3 [Member] | San Diego Gas and Electric Company [Member] | Maximum [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Congestion revenue rights (in dollars per MWH)			6.03		35.21
Market electricity forward price inputs ( in dollars per MWH)	51.60	62.65	51.60	62.65
Level 3 [Member] | San Diego Gas and Electric Company [Member] | Weighted Average [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Congestion revenue rights (in dollars per MWH)			(1.58)		$ (2.94)
Market electricity forward price inputs ( in dollars per MWH)	$ 34.68	$ 41.50	$ 34.68	$ 41.50