FAIR VALUE MEASUREMENTS - RECON OF LEVEL 3 ASSETS (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 17,000,000	$ 176,000,000	$ 28,000,000	$ 179,000,000	$ 179,000,000
Realized and unrealized losses	(4,000,000)	(24,000,000)	(18,000,000)	(32,000,000)
Allocated transmission instruments	1,000,000	0	2,000,000	0
Settlements	19,000,000	27,000,000	21,000,000	32,000,000
Ending balance	33,000,000	179,000,000	33,000,000	179,000,000	28,000,000
Change in unrealized gains (losses) relating to instruments still held at the end of the period	7,000,000	1,000,000	(1,000,000)	12,000,000
Sempra LNG [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Change in unrealized gains (losses) relating to instruments still held at the end of the period	6,000,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0
Realized and unrealized gains	7,000,000
Settlements	(1,000,000)
Ending balance	6,000,000		6,000,000
San Diego Gas and Electric Company [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	17,000,000	176,000,000	28,000,000	179,000,000	179,000,000
Realized and unrealized losses	(4,000,000)	(24,000,000)	(18,000,000)	(32,000,000)
Allocated transmission instruments	1,000,000	0	2,000,000	0
Settlements	19,000,000	27,000,000	21,000,000	32,000,000
Ending balance	33,000,000	179,000,000	33,000,000	179,000,000	28,000,000
Change in unrealized gains (losses) relating to instruments still held at the end of the period	7,000,000	1,000,000	(1,000,000)	12,000,000
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)	19.45	21.60	19.45	21.60
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)	71.25	57.20	71.25	57.20
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)	$ 38.14	$ 38.29	$ 38.14	$ 38.29

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Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

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