FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 10
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	411	$ 496
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	53	54
Nuclear decomissioning trusts - Municipal debt securities	269	250
Nuclear decommissioning trusts - Other debt securities	234	217
Nuclear decommissioning trusts - Total debt securities	556	521
Total nuclear decommissioning trusts	967	1,017
Assets fair value disclosure, total	1,334	1,188
Liabilities fair value disclosure, total	288	384
Fair Value, Measurements, Recurring [Member] | Interest Rate and Foreign Exchange Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	2	7
Derivative liability	150	217
Fair Value, Measurements, Recurring [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	24	17
Effect of netting and allocation of collateral	19	2
Derivative liability	34	6
Fair Value, Measurements, Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	289	128
Effect of netting and allocation of collateral	33	17
Derivative liability	106	184
Effect of netting and allocation of collateral	(2)	(23)
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	407	491
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	43	45
Nuclear decomissioning trusts - Municipal debt securities	0	0
Nuclear decommissioning trusts - Other debt securities	0	0
Nuclear decommissioning trusts - Total debt securities	43	45
Total nuclear decommissioning trusts	450	536
Assets fair value disclosure, total	499	555
Liabilities fair value disclosure, total	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Interest Rate and Foreign Exchange Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	5
Effect of netting and allocation of collateral	19	2
Derivative liability	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	2	0
Effect of netting and allocation of collateral	28	12
Derivative liability	2	23
Effect of netting and allocation of collateral	(2)	(23)
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	4	5
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	10	9
Nuclear decomissioning trusts - Municipal debt securities	269	250
Nuclear decommissioning trusts - Other debt securities	234	217
Nuclear decommissioning trusts - Total debt securities	513	476
Total nuclear decommissioning trusts	517	481
Assets fair value disclosure, total	552	502
Liabilities fair value disclosure, total	189	230
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest Rate and Foreign Exchange Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	2	7
Derivative liability	150	217
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	24	12
Effect of netting and allocation of collateral	0	0
Derivative liability	34	6
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	9	2
Effect of netting and allocation of collateral	0	0
Derivative liability	5	7
Effect of netting and allocation of collateral	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	0	0
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	0	0
Nuclear decomissioning trusts - Municipal debt securities	0	0
Nuclear decommissioning trusts - Other debt securities	0	0
Nuclear decommissioning trusts - Total debt securities	0	0
Total nuclear decommissioning trusts	0	0
Assets fair value disclosure, total	283	131
Liabilities fair value disclosure, total	99	154
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest Rate and Foreign Exchange Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Effect of netting and allocation of collateral	0	0
Derivative liability	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	278	126
Effect of netting and allocation of collateral	5	5
Derivative liability	99	154
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	411	496
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	53	54
Nuclear decomissioning trusts - Municipal debt securities	269	250
Nuclear decommissioning trusts - Other debt securities	234	217
Nuclear decommissioning trusts - Total debt securities	556	521
Total nuclear decommissioning trusts	967	1,017
Assets fair value disclosure, total	1,280	1,159
Liabilities fair value disclosure, total	100	172
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	285	126
Effect of netting and allocation of collateral	28	16
Derivative liability	101	182
Effect of netting and allocation of collateral	(2)	(23)
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	1	13
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	407	491
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	43	45
Nuclear decomissioning trusts - Municipal debt securities	0	0
Nuclear decommissioning trusts - Other debt securities	0	0
Nuclear decommissioning trusts - Total debt securities	43	45
Total nuclear decommissioning trusts	450	536
Assets fair value disclosure, total	474	547
Liabilities fair value disclosure, total	0	0
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	1	0
Effect of netting and allocation of collateral	23	11
Derivative liability	2	23
Effect of netting and allocation of collateral	(2)	(23)
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	0	0
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	4	5
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	10	9
Nuclear decomissioning trusts - Municipal debt securities	269	250
Nuclear decommissioning trusts - Other debt securities	234	217
Nuclear decommissioning trusts - Total debt securities	513	476
Total nuclear decommissioning trusts	517	481
Assets fair value disclosure, total	523	481
Liabilities fair value disclosure, total	1	18
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	6	0
Effect of netting and allocation of collateral	0	0
Derivative liability	0	5
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	1	13
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	0	0
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	0	0
Nuclear decomissioning trusts - Municipal debt securities	0	0
Nuclear decommissioning trusts - Other debt securities	0	0
Nuclear decommissioning trusts - Total debt securities	0	0
Total nuclear decommissioning trusts	0	0
Assets fair value disclosure, total	283	131
Liabilities fair value disclosure, total	99	154
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	278	126
Effect of netting and allocation of collateral	5	5
Derivative liability	99	154
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	0	0
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	9	3
Liabilities fair value disclosure, total	5	2
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	4	2
Effect of netting and allocation of collateral	5	1
Derivative liability	5	2
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	6	1
Liabilities fair value disclosure, total	0	0
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	1	0
Effect of netting and allocation of collateral	5	1
Derivative liability	0	0
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	3	2
Liabilities fair value disclosure, total	5	2
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	3	2
Effect of netting and allocation of collateral	0	0
Derivative liability	5	2
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	0	0
Liabilities fair value disclosure, total	0	0
Southern California Gas Company [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Effect of netting and allocation of collateral	0	0
Derivative liability	$ 0	$ 0