COMMITMENTS AND CONTINGENCIES - LEGAL PROCEEDINGS (Details)		1 Months Ended				3 Months Ended			9 Months Ended
	Nov. 02, 2018 plaintiff lawsuit	Oct. 31, 2018 plaintiff	Aug. 31, 2018 USD ($)	Jan. 31, 2017 lawsuit	Sep. 30, 2016 USD ($)	Sep. 30, 2018 USD ($) Bcf lawsuit	Sep. 30, 2017 USD ($)		Sep. 30, 2018 USD ($) Bcf lawsuit	Sep. 30, 2017 USD ($)		Dec. 31, 2017 USD ($)	[2]	Oct. 21, 2016 t
Loss Contingencies [Line Items]
Liability for legal proceedings						$ 230,000,000			$ 230,000,000
Write-off of wildfire regulatory asset						0	$ 351,000,000	[1]	0	$ 351,000,000	[1]
Reserve for Aliso Canyon costs						161,000,000			161,000,000			$ 84,000,000
Insurance receivable for Aliso Canyon costs						$ 474,000,000			474,000,000			418,000,000
Consolidated Class Action Complaints [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed | lawsuit				2
Property Class Action [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed | lawsuit				1
Complaints Filed by Public Entities [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed | lawsuit						3
San Diego Gas and Electric Company [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings						$ 3,000,000			3,000,000
Write-off of wildfire regulatory asset						0	351,000,000		0	351,000,000	[3]
San Diego Gas and Electric Company [Member] | Wildfire [Member]
Loss Contingencies [Line Items]
Write-off of wildfire regulatory asset							351,000,000
After-tax charge for nonrecovery of CPUC regulatory assets							$ 208,000,000			$ 208,000,000
Southern California Gas Company [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings						176,000,000			176,000,000
Insurance Settlements Receivable						1,012,000,000			1,012,000,000
Reserve for Aliso Canyon costs						161,000,000			161,000,000			84,000,000
Insurance receivable for Aliso Canyon costs						474,000,000			474,000,000			$ 418,000,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings						127,000,000			127,000,000
Loss contingency accrual						$ 1,039,000,000			$ 1,039,000,000
Percent of Loss Accrual Allocated to Temporary Relocation Program						55.00%			55.00%
Reserve for Aliso Canyon costs						$ 161,000,000			$ 161,000,000
Receivable related to natural gas leak						$ 474,000,000			474,000,000
Insurance proceeds									$ 538,000,000
Loss Contingency, Total Actual Emissions, Floor (in metric tons) | t														90,350
Loss Contingency, Total Actual Emissions, Ceiling (in metric tons) | t														108,950
Mitigation requirements (in metric tons) | t														109,000
Amount of natural gas released | Bcf									4.62
Storage facility capacity | Bcf						86			86
Proportion of total gas storage capacity (percentage)						63.00%			63.00%
Storage Facility, Working Gas Target | Bcf						34			34
Net book value of Aliso Canyon facility						$ 696,000,000			$ 696,000,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member] | Compressor Station [Member]
Loss Contingencies [Line Items]
Net book value of Aliso Canyon facility						285,000,000			285,000,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit	388
Number of plaintiffs | plaintiff	48,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Liability insurance coverage						1,200,000,000			1,200,000,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Liability insurance coverage						$ 1,400,000,000			$ 1,400,000,000
Southern California Gas Company [Member] | Damages from Product Defects [Member]
Loss Contingencies [Line Items]
Maximum occupational safety and health fines					$ 75,000
Penalty assessments					233,500
Maximum other assessments in settlement of criminal complaint					$ 6,000,000
Southern California Gas Company [Member] | Complaints Filed by Firefighters [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Number of plaintiffs | plaintiff		36
Southern California Gas Company [Member] | Complaints Filed by Public Entities [Member] | Funding for Environmental Projects [Member]
Loss Contingencies [Line Items]
Settlement amount payable			$ 120,000,000
Southern California Gas Company [Member] | Complaints Filed by Public Entities [Member] | Civil Penalties [Member]
Loss Contingencies [Line Items]
Settlement amount payable			$ 21,000,000
Energy Future Holdings Corp. [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit						115			115

[1] As adjusted for the retrospective adoption of ASU 2017-07, which we discuss in Note 2, and a reclassification to conform to current year presentation, which we discuss in Note 1.

[2] Derived from audited financial statements.

[3] As adjusted for the retrospective adoption of ASU 2016-15 and ASU 2016-18, which we discuss in Note 2.