REVENUES - CONTRACT LIABILITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contract with Customer, Liability [Roll Forward]
Beginning balance	$ (163)	$ (70)	$ 0
Revenue from performance obligations satisfied during reporting period	4	2	7
Payments received in advance	(48)	(95)	(16)
Ending balance	(207)	(163)	(70)
Cumulative Effect, Period of Adoption, Adjustment
Contract with Customer, Liability [Roll Forward]
Beginning balance	0	0	(61)
Ending balance		0	0
Other Current Liabilities [Member]
Contract with Customer, Liability [Roll Forward]
Beginning balance	(4)
Ending balance	(52)	(4)
Deferred Credits and Other [Member]
Contract with Customer, Liability [Roll Forward]
Beginning balance	(159)
Ending balance	(155)	(159)
San Diego Gas and Electric Company [Member]
Contract with Customer, Liability [Roll Forward]
Beginning balance	(91)	0
Revenue from performance obligations satisfied during reporting period	4	1
Payments received in advance	0	(92)
Ending balance	(87)	(91)	$ 0
San Diego Gas and Electric Company [Member] | Other Current Liabilities [Member]
Contract with Customer, Liability [Roll Forward]
Beginning balance	(4)
Ending balance	(4)	(4)
San Diego Gas and Electric Company [Member] | Deferred Credits and Other [Member]
Contract with Customer, Liability [Roll Forward]
Beginning balance	(87)
Ending balance	$ (83)	$ (87)