REGULATORY MATTERS - COST OF CAPITAL & FERC (Details) - San Diego Gas and Electric Company [Member] - USD ($) $ in Millions	1 Months Ended		3 Months Ended			12 Months Ended
	Mar. 31, 2020	Oct. 31, 2019	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020
Public Utilities, General Disclosures [Line Items]
FERC requirement to maintain common equity ratio, at or above (percent)		10.60%
Base ROE		10.10%
Additional Bps		0.50%
Additional FERC revenues					$ 12
Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Additional FERC revenues					$ 17
California Public Utilities Commission [Member] | Energy Efficiency Program Inquiry [Member]
Public Utilities, General Disclosures [Line Items]
Equity losses on investment			$ 36	$ 15
Litigation fines			$ 6
Loss contingency, loss in period, after tax						$ 44
Common Equity [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity, percentage	10.05%