COMMITMENTS AND CONTINGENCIES - LEGAL PROCEEDINGS (Details)					1 Months Ended			3 Months Ended		9 Months Ended
	Oct. 31, 2017 plaintiff lawsuit	Jul. 19, 2017 Bcf	Mar. 13, 2017	Mar. 31, 2016 t	Feb. 28, 2017 USD ($)	Jan. 31, 2017 lawsuit	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Bcf lawsuit	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Bcf lawsuit	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	[1]	Oct. 21, 2016 t
Loss Contingencies [Line Items]
Liability for legal proceedings								$ 5,000,000		$ 5,000,000
Impairment of wildfire regulatory asset								351,000,000	$ 0	351,000,000	$ 0
Percent of arbitration expenses reduction of award			95.00%
Reserve for Aliso Canyon costs								42,000,000		42,000,000		$ 53,000,000
Insurance receivable for Aliso Canyon costs								542,000,000		542,000,000		606,000,000
Aliso Canyon Natural Gas Storage Facility Gas Leak [Member]
Loss Contingencies [Line Items]
Reserve for Aliso Canyon costs								42,000,000		42,000,000
Insurance receivable for Aliso Canyon costs								$ 542,000,000		$ 542,000,000
Property Disputes [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed | lawsuit										2
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]
Settlement paid					$ 8,500,000
Number of lawsuits filed | lawsuit								3
Complaints Filed by Public Entities [Member] | Health Study [Member]
Loss Contingencies [Line Items]
Settlement paid					$ 1,000,000
San Diego Gas and Electric Company [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings								$ 3,000,000		$ 3,000,000
Impairment of wildfire regulatory asset								351,000,000		351,000,000	$ 0
San Diego Gas and Electric Company [Member] | Wildfire [Member]
Loss Contingencies [Line Items]
Impairment of wildfire regulatory asset								351,000,000
After-tax charge for nonrecovery of CPUC regulatory assets								208,000,000		208,000,000
San Diego Gas and Electric Company [Member] | Lawsuit Against MHI [Member]
Loss Contingencies [Line Items]
Percent of arbitration expenses reduction of award			95.00%
Southern California Gas Company [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings								1,000,000		1,000,000
Reserve for Aliso Canyon costs								42,000,000		42,000,000		53,000,000
Insurance receivable for Aliso Canyon costs								542,000,000		542,000,000		$ 606,000,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member]
Loss Contingencies [Line Items]
Liability for legal proceedings								1,000,000		1,000,000
Loss contingency accrual								841,000,000		841,000,000
Reserve for Aliso Canyon costs								42,000,000		42,000,000
Insurance receivable for Aliso Canyon costs								$ 542,000,000		542,000,000
Insurance proceeds										$ 294,000,000
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
Required working gas target | Bcf		23.6
Required working gas minimum | Bcf		14.8
Storage facility capacity | Bcf								86		86
Proportion of total gas storage capacity (percentage)		28.00%						63.00%		63.00%
Net book value of Aliso Canyon facility								$ 609,000,000		$ 609,000,000
Construction work in progress of new compressor station								244,000,000		244,000,000
Southern California Gas Company [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Number of lawsuits filed | lawsuit	344
Number of plaintiffs | plaintiff	43,826
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
Environmental mitigation period				5 years
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
Environmental mitigation period				10 years
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							$ 5,000,000

[1] Derived from audited financial statements.