COMMITMENTS AND CONTINGENCIES - LEGAL PROCEEDINGS (Details)			1 Months Ended		3 Months Ended		6 Months Ended
	Aug. 01, 2018 plaintiff lawsuit	Mar. 31, 2016 t	Jan. 31, 2017 lawsuit	Sep. 30, 2016 USD ($)	Jun. 30, 2018 USD ($) Bcf lawsuit	Sep. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Bcf	Dec. 31, 2017 USD ($)	[1]	Oct. 21, 2016 t
Loss Contingencies [Line Items]
Liability for legal proceedings					$ 191,000,000		$ 191,000,000
Reserve for Aliso Canyon costs					160,000,000		160,000,000	$ 84,000,000
Insurance receivable for Aliso Canyon costs					$ 502,000,000		502,000,000	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					$ 2,000,000		2,000,000
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
Southern California Gas Company [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings					136,000,000		136,000,000
Insurance Settlements Receivable					987,000,000		987,000,000
Reserve for Aliso Canyon costs					160,000,000		160,000,000	84,000,000
Insurance receivable for Aliso Canyon costs					502,000,000		502,000,000	$ 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					$ 1,014,000,000		$ 1,014,000,000
Percent of Loss Accrual Allocated to Temporary Relocation Program					55.00%		55.00%
Reserve for Aliso Canyon costs					$ 160,000,000		$ 160,000,000
Receivable related to natural gas leak					$ 502,000,000		502,000,000
Insurance proceeds							$ 485,000,000
Period of required climate reductions		20 years
Period of required regulatory climate reductions		100 years
Target emissions level (in metric tons) | t		9,000,000
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					$ 678,000,000		$ 678,000,000
Construction work in progress of new compressor station					286,000,000		286,000,000
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	382
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

[1] Derived from audited financial statements.