REGULATORY MATTERS - COST OF CAPITAL & FERC RATES (Details)	9 Months Ended	12 Months Ended	24 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2019
Southern California Gas Company [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Weighted return on rate base	8.02%	8.02%
Cost of debt	5.77%
Southern California Gas Company [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			100.00%
Change in return on rate base			(0.68%)
Weighted return on rate base			7.34%
Change in cost of debt			(1.44%)
Cost of debt			4.33%
Southern California Gas Company [Member] | Capital Structure, Long Term Debt [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			45.60%
Return on rate base			4.33%
Weighted return on rate base			1.97%
Southern California Gas Company [Member] | Capital Structure, Preferred Stock [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			2.40%
Return on rate base			6.00%
Weighted return on rate base			0.14%
Southern California Gas Company [Member] | Capital Structure, Common Equity [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			52.00%
Return on rate base			10.05%
Weighted return on rate base			5.23%
San Diego Gas and Electric Company [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Weighted return on rate base	7.79%	7.79%
Cost of debt	5.00%
San Diego Gas and Electric Company [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Weighting		100.00%
Weighted return on rate base		7.51%
San Diego Gas and Electric Company [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			100.00%
Change in return on rate base			(0.24%)
Weighted return on rate base			7.55%
Change in cost of debt			(0.41%)
Cost of debt			4.59%
San Diego Gas and Electric Company [Member] | Capital Structure, Long Term Debt [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Weighting		43.44%
Return on rate base		4.21%
Weighted return on rate base		1.83%
San Diego Gas and Electric Company [Member] | Capital Structure, Long Term Debt [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			45.25%
Return on rate base			4.59%
Weighted return on rate base			2.08%
San Diego Gas and Electric Company [Member] | Capital Structure, Preferred Stock [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			2.75%
Return on rate base			6.22%
Weighted return on rate base			0.17%
San Diego Gas and Electric Company [Member] | Capital Structure, Common Equity [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Weighting		56.56%
Return on rate base		10.05%
Weighted return on rate base		5.68%
San Diego Gas and Electric Company [Member] | Capital Structure, Common Equity [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Authorized weighting			52.00%
Return on rate base			10.20%
Weighted return on rate base			5.30%
Cost of Capital [Member] | Southern California Gas Company [Member] | Capital Structure, Common Equity [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Return on rate base	10.10%
Cost of Capital [Member] | Southern California Gas Company [Member] | Capital Structure, Common Equity [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Return on rate base			10.05%
Cost of Capital [Member] | San Diego Gas and Electric Company [Member] | Capital Structure, Common Equity [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Return on rate base	10.30%
Cost of Capital [Member] | San Diego Gas and Electric Company [Member] | Capital Structure, Common Equity [Member] | Scenario, Forecast [Member] | California Public Utilities Commission [Member]
Public Utilities, General Disclosures [Line Items]
Return on rate base			10.20%