OTHER FINANCIAL DATA - GREENHOUSE GAS ALLOWANCES (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Regulatory Assets [Abstract]
Sundry	$ 3,186	$ 3,414	[1]
Greenhouse Gas Allowance [Member]
Regulatory Assets [Abstract]
Other current assets	40	40
Sundry	352	295
Total assets	392	335
Greenhouse Gas Obligation [Member]
Regulatory Liabilities [Abstract]
Other current liabilities	40	40
Deferred credits and other	240	171
Total liabilities	280	211
San Diego Gas and Electric Company [Member]
Regulatory Assets [Abstract]
Other current assets	112	81	[1]
Sundry	572	998	[1]
San Diego Gas and Electric Company [Member] | Greenhouse Gas Allowance [Member]
Regulatory Assets [Abstract]
Other current assets	16	16
Sundry	190	182
Total assets	206	198
San Diego Gas and Electric Company [Member] | Greenhouse Gas Obligation [Member]
Regulatory Liabilities [Abstract]
Other current liabilities	16	16
Deferred credits and other	105	72
Total liabilities	121	88
Southern California Gas Company [Member]
Regulatory Assets [Abstract]
Other current assets	8	8	[1]
Sundry	692	589	[1]
Southern California Gas Company [Member] | Greenhouse Gas Allowance [Member]
Regulatory Assets [Abstract]
Other current assets	24	24
Sundry	159	109
Total assets	183	133
Southern California Gas Company [Member] | Greenhouse Gas Obligation [Member]
Regulatory Liabilities [Abstract]
Other current liabilities	24	24
Deferred credits and other	131	96
Total liabilities	$ 155	$ 120

[1] Derived from audited financial statements.