COMMITMENTS AND CONTINGENCIES - SITE CONTINGENCY (Details) $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2016 USD ($)	Dec. 31, 2017 USD ($)
Site Contingency [Line Items]
Accrual for environmental loss contingencies		$ 29
Accrual for environmental loss contingencies, current		9
Accrual for environmental loss contingencies, noncurrent		20
SONGS mitigation costs remaining	$ 4,400
Manufactured Gas Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		22
Waste Disposal Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		4
Other Hazardous Waste Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		3
San Diego Gas and Electric Company [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		4
Accrual for environmental loss contingencies, current		1
Accrual for environmental loss contingencies, noncurrent		3
Estimated SONGS mitigation costs, recoverable in rates		68
SONGS mitigation costs incurred		44
SONGS mitigation costs remaining	$ 899	$ 24
San Diego Gas and Electric Company [Member] | Manufactured Gas Sites [Member]
Site Contingency [Line Items]
Site Contingency, Sites Completed		3
Site Contingency, Sites In Process		0
Accrual for environmental loss contingencies		$ 0
San Diego Gas and Electric Company [Member] | Waste Disposal Sites [Member]
Site Contingency [Line Items]
Site Contingency, Sites Completed		2
Site Contingency, Sites In Process		1
Accrual for environmental loss contingencies		$ 2
San Diego Gas and Electric Company [Member] | Other Hazardous Waste Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		2
San Diego Gas and Electric Company [Member] | California Coastal Reef Expansion [Member]
Site Contingency [Line Items]
SONGS mitigation costs remaining		4
Southern California Gas Company [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		24
Accrual for environmental loss contingencies, current		8
Accrual for environmental loss contingencies, noncurrent		$ 16
Southern California Gas Company [Member] | Manufactured Gas Sites [Member]
Site Contingency [Line Items]
Site Contingency, Sites Completed		39
Site Contingency, Sites In Process		3
Accrual for environmental loss contingencies		$ 22
Southern California Gas Company [Member] | Waste Disposal Sites [Member]
Site Contingency [Line Items]
Site Contingency, Sites Completed		5
Site Contingency, Sites In Process		2
Accrual for environmental loss contingencies		$ 1
Southern California Gas Company [Member] | Other Hazardous Waste Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		1
Other Sempra Energy [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		1
Other Sempra Energy [Member] | Manufactured Gas Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		0
Other Sempra Energy [Member] | Waste Disposal Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		1
Other Sempra Energy [Member] | Other Hazardous Waste Sites [Member]
Site Contingency [Line Items]
Accrual for environmental loss contingencies		$ 0