FAIR VALUE MEASUREMENTS - RECON OF LEVEL 3 ASSETS (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) $ / MWh	Sep. 30, 2020 USD ($) $ / MWh	Sep. 30, 2021 USD ($) $ / MWh	Sep. 30, 2020 USD ($) $ / MWh
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 80	$ 17	$ 69	$ 28
Realized and unrealized losses	(35)	(4)	(29)	(18)
Allocated transmission instruments	1	1	(1)	2
Settlements	26	19	33	21
Ending balance	72	33	72	33
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	9	7	5	(1)
Sempra LNG [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	4	0	3	0
Realized and unrealized gains	3	7	8	7
Settlements	(2)	(1)	(6)	(1)
Ending balance	5	6	5	6
Change in unrealized gains (losses) relating to instruments still held at the end of the period	3	6	7	6
Sempra LNG [Member] | Other current assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
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	2		2
San Diego Gas and Electric Company [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	80	17	69	28
Realized and unrealized losses	(35)	(4)	(29)	(18)
Allocated transmission instruments	1	1	(1)	2
Settlements	26	19	33	21
Ending balance	72	33	72	33
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 9	$ 7	$ 5	$ (1)
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	24.05	19.45	24.05	19.45
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	130.40	71.25	130.40	71.25
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	57.36	38.14	57.36	38.14