FAIR VALUE MEASUREMENTS - RECON OF LEVEL 3 ASSETS (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) $ / MWh	Jun. 30, 2020 USD ($) $ / MWh	Jun. 30, 2021 USD ($) $ / MWh	Jun. 30, 2020 USD ($) $ / MWh
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 62	$ 16	$ 69	$ 28
Realized and unrealized gains (losses)	8	(9)	6	(14)
Allocated transmission instruments	(2)	1	(2)	1
Settlements	12	9	7	2
Ending balance	80	17	80	17
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	14	(5)	12	(13)
Sempra LNG [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3		3
Realized and unrealized gains	3		5
Settlements	(2)		(4)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Ending Balance	4		4
Change in unrealized gains (losses) relating to instruments still held at the end of the period	2		4
Sempra LNG [Member] | Other current assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Ending Balance	7		7
Sempra LNG [Member] | Deferred Credits and Other [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	3		3
San Diego Gas and Electric Company [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	62	16	69	28
Realized and unrealized gains (losses)	8	(9)	6	(14)
Allocated transmission instruments	(2)	1	(2)	1
Settlements	12	9	7	2
Ending balance	80	17	80	17
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 14	$ (5)	$ 12	$ (13)
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) | $ / MWh			(1.81)	(3.77)
Market electricity forward price inputs ( in dollars per MWH) | $ / MWh	22.45	20.35	22.45	20.35
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) | $ / MWh			14.11	6.03
Market electricity forward price inputs ( in dollars per MWH) | $ / MWh	151.90	51.60	151.90	51.60
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) | $ / MWh			(0.12)	(1.58)
Market electricity forward price inputs ( in dollars per MWH) | $ / MWh	49.27	34.68	49.27	34.68