FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
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	$ 5	$ 10
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	509	411
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	57	53
Nuclear decommissioning trusts - Municipal debt securities	282	269
Nuclear decommissioning trusts - Other debt securities	226	234
Nuclear decommissioning trusts - Total debt securities	565	556
Total nuclear decommissioning trusts	1,074	967
Assets fair value disclosure, total	1,285	1,334
Liabilities fair value disclosure, total	245	288
Fair Value, Recurring [Member] | Interest Rate and Foreign Exchange Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	24	2
Derivative liability	157	150
Fair Value, 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	11	24
Effect of netting and allocation of collateral	43	19
Derivative liability	17	34
Fair Value, Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	108	289
Effect of netting and allocation of collateral	25	33
Derivative liability	85	106
Effect of netting and allocation of collateral	(14)	(2)
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	503	407
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	46	43
Nuclear decommissioning trusts - Municipal debt securities	0	0
Nuclear decommissioning trusts - Other debt securities	0	0
Nuclear decommissioning trusts - Total debt securities	46	43
Total nuclear decommissioning trusts	549	450
Assets fair value disclosure, total	608	499
Liabilities fair value disclosure, total	0	0
Fair Value, 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, 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	0
Effect of netting and allocation of collateral	43	19
Derivative liability	0	0
Fair Value, 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	5	2
Effect of netting and allocation of collateral	11	28
Derivative liability	14	2
Effect of netting and allocation of collateral	(14)	(2)
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	6	4
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	11	10
Nuclear decommissioning trusts - Municipal debt securities	282	269
Nuclear decommissioning trusts - Other debt securities	226	234
Nuclear decommissioning trusts - Total debt securities	519	513
Total nuclear decommissioning trusts	525	517
Assets fair value disclosure, total	576	552
Liabilities fair value disclosure, total	178	189
Fair Value, 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	24	2
Derivative liability	157	150
Fair Value, 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	11	24
Effect of netting and allocation of collateral	0	0
Derivative liability	17	34
Fair Value, 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	8	9
Effect of netting and allocation of collateral	8	0
Derivative liability	4	5
Effect of netting and allocation of collateral	0	0
Fair Value, 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 decommissioning 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	101	283
Liabilities fair value disclosure, total	67	99
Fair Value, 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, 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, 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	95	278
Effect of netting and allocation of collateral	6	5
Derivative liability	67	99
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	509	411
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	57	53
Nuclear decommissioning trusts - Municipal debt securities	282	269
Nuclear decommissioning trusts - Other debt securities	226	234
Nuclear decommissioning trusts - Total debt securities	565	556
Total nuclear decommissioning trusts	1,074	967
Assets fair value disclosure, total	1,189	1,280
Liabilities fair value disclosure, total	67	100
San Diego Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	99	285
Effect of netting and allocation of collateral	16	28
Derivative liability	81	101
Effect of netting and allocation of collateral	(14)	(2)
San Diego Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability		1
San Diego Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	503	407
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	46	43
Nuclear decommissioning trusts - Municipal debt securities	0	0
Nuclear decommissioning trusts - Other debt securities	0	0
Nuclear decommissioning trusts - Total debt securities	46	43
Total nuclear decommissioning trusts	549	450
Assets fair value disclosure, total	560	474
Liabilities fair value disclosure, total	0	0
San Diego Gas and Electric Company [Member] | Fair Value, 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	1
Effect of netting and allocation of collateral	10	23
Derivative liability	14	2
Effect of netting and allocation of collateral	(14)	(2)
San Diego Gas and Electric Company [Member] | Fair Value, 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
San Diego Gas and Electric Company [Member] | Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	6	4
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	11	10
Nuclear decommissioning trusts - Municipal debt securities	282	269
Nuclear decommissioning trusts - Other debt securities	226	234
Nuclear decommissioning trusts - Total debt securities	519	513
Total nuclear decommissioning trusts	525	517
Assets fair value disclosure, total	528	523
Liabilities fair value disclosure, total	0	1
San Diego Gas and Electric Company [Member] | Fair Value, 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	6
Effect of netting and allocation of collateral	0	0
Derivative liability	0	0
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Fair Value, 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
San Diego Gas and Electric Company [Member] | Fair Value, 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 decommissioning 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	101	283
Liabilities fair value disclosure, total	67	99
San Diego Gas and Electric Company [Member] | Fair Value, 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	95	278
Effect of netting and allocation of collateral	6	5
Derivative liability	67	99
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Fair Value, 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
Southern California Gas Company [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	18	9
Liabilities fair value disclosure, total	4	5
Southern California Gas Company [Member] | Fair Value, Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	9	4
Effect of netting and allocation of collateral	9	5
Derivative liability	4	5
Southern California Gas Company [Member] | Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	5	6
Liabilities fair value disclosure, total	0	0
Southern California Gas Company [Member] | Fair Value, 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	4	1
Effect of netting and allocation of collateral	1	5
Derivative liability	0	0
Southern California Gas Company [Member] | Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value disclosure, total	13	3
Liabilities fair value disclosure, total	4	5
Southern California Gas Company [Member] | Fair Value, 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	5	3
Effect of netting and allocation of collateral	8	0
Derivative liability	4	5
Southern California Gas Company [Member] | Fair Value, 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, 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