OTHER FINANCIAL DATA - GREENHOUSE GAS (GHG) ALLOWANCES (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Regulatory Assets [Abstract]
Sundry	$ 3,503	$ 3,414	[1]
Greenhouse Gas Allowance [Member]
Regulatory Assets [Abstract]
Other current assets	40	40
Sundry	307	295
Total assets	347	335
Greenhouse Gas Obligation [Member]
Regulatory LIabilities [Abstract]
Other current liabilities	40	40
Deferred credits and other	183	171
Total liabilities	223	211
San Diego Gas and Electric Company [Member]
Regulatory Assets [Abstract]
Other current assets	99	81	[1]
Sundry	1,018	998	[1]
San Diego Gas and Electric Company [Member] | Greenhouse Gas Allowance [Member]
Regulatory Assets [Abstract]
Other current assets	16	16
Sundry	184	182
Total assets	200	198
San Diego Gas and Electric Company [Member] | Greenhouse Gas Obligation [Member]
Regulatory LIabilities [Abstract]
Other current liabilities	16	16
Deferred credits and other	80	72
Total liabilities	96	88
Southern California Gas Company [Member]
Regulatory Assets [Abstract]
Other current assets	6	8	[1]
Sundry	661	589	[1]
Southern California Gas Company [Member] | Greenhouse Gas Allowance [Member]
Regulatory Assets [Abstract]
Other current assets	24	24
Sundry	119	109
Total assets	143	133
Southern California Gas Company [Member] | Greenhouse Gas Obligation [Member]
Regulatory LIabilities [Abstract]
Other current liabilities	24	24
Deferred credits and other	99	96
Total liabilities	$ 123	$ 120

[1] Derived from audited financial statements.