FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	$ 367	$ 364
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	61	65
Nuclear decommissioning trusts - Municipal bonds	324	326
Nuclear decommissioning trusts - Other securities	268	270
Nuclear decommissioning trusts - Total debt securities	653	661
Total nuclear decommissioning trusts	1,020	1,025
Support Agreement, net of related guarantee fees	7	7
Total Assets Measured at Fair Value	1,247	1,240
Support Agreement, net of related guarantee fees	3	4
Total Liabilities Measured at Fair Value	246	264
Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	5	25
Derivative liabilities	183	186
Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	4	4
Effect of netting and allocation of collateral	59	21
Derivative liabilities	36	16
Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	125	128
Effect of netting and allocation of collateral	27	30
Derivative liabilities	24	58
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	361	358
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	48	41
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	48	41
Total nuclear decommissioning trusts	409	399
Support Agreement, net of related guarantee fees	0	0
Total Assets Measured at Fair Value	503	445
Support Agreement, net of related guarantee fees	0	0
Total Liabilities Measured at Fair Value	0	0
Level 1 [Member] | Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
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 assets	0	0
Effect of netting and allocation of collateral	59	21
Derivative liabilities	0	0
Level 1 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	14	6
Effect of netting and allocation of collateral	21	19
Derivative liabilities	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	6	6
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	13	24
Nuclear decommissioning trusts - Municipal bonds	324	326
Nuclear decommissioning trusts - Other securities	268	270
Nuclear decommissioning trusts - Total debt securities	605	620
Total nuclear decommissioning trusts	611	626
Support Agreement, net of related guarantee fees	0	0
Total Assets Measured at Fair Value	635	661
Support Agreement, net of related guarantee fees	0	0
Total Liabilities Measured at Fair Value	227	208
Level 2 [Member] | Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	5	25
Derivative liabilities	183	186
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 assets	4	4
Effect of netting and allocation of collateral	0	0
Derivative liabilities	36	16
Level 2 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	15	1
Effect of netting and allocation of collateral	0	5
Derivative liabilities	8	6
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 bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	0	0
Total nuclear decommissioning trusts	0	0
Support Agreement, net of related guarantee fees	7	7
Total Assets Measured at Fair Value	109	134
Support Agreement, net of related guarantee fees	3	4
Total Liabilities Measured at Fair Value	19	56
Level 3 [Member] | Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
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 assets	0	0
Effect of netting and allocation of collateral	0	0
Derivative liabilities	0	0
Level 3 [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	96	121
Effect of netting and allocation of collateral	6	6
Derivative liabilities	16	52
San Diego Gas and Electric Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	367	364
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	61	65
Nuclear decommissioning trusts - Municipal bonds	324	326
Nuclear decommissioning trusts - Other securities	268	270
Nuclear decommissioning trusts - Total debt securities	653	661
Total nuclear decommissioning trusts	1,020	1,025
Total Assets Measured at Fair Value	1,162	1,175
Total Liabilities Measured at Fair Value	16	52
San Diego Gas and Electric Company [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	116	126
Effect of netting and allocation of collateral	26	24
Derivative liabilities	16	52
San Diego Gas and Electric Company [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	361	358
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	48	41
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	48	41
Total nuclear decommissioning trusts	409	399
Total Assets Measured at Fair Value	443	422
Total Liabilities Measured at Fair Value	0	0
San Diego Gas and Electric Company [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 assets	14	5
Effect of netting and allocation of collateral	20	18
Derivative liabilities	0	0
San Diego Gas and Electric Company [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	6	6
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	13	24
Nuclear decommissioning trusts - Municipal bonds	324	326
Nuclear decommissioning trusts - Other securities	268	270
Nuclear decommissioning trusts - Total debt securities	605	620
Total nuclear decommissioning trusts	611	626
Total Assets Measured at Fair Value	617	626
Total Liabilities Measured at Fair Value	0	0
San Diego Gas and Electric Company [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 assets	6	0
Effect of netting and allocation of collateral	0	0
Derivative liabilities	0	0
San Diego Gas and Electric Company [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 bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	0	0
Total nuclear decommissioning trusts	0	0
Total Assets Measured at Fair Value	102	127
Total Liabilities Measured at Fair Value	16	52
San Diego Gas and Electric Company [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 assets	96	121
Effect of netting and allocation of collateral	6	6
Derivative liabilities	16	52
Southern California Gas Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	10	8
Total Liabilities Measured at Fair Value	8	6
Southern California Gas Company [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	9	2
Effect of netting and allocation of collateral	1	6
Derivative liabilities	8	6
Southern California Gas Company [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	1	2
Total Liabilities Measured at Fair Value	0	0
Southern California Gas Company [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 assets	0	1
Effect of netting and allocation of collateral	1	1
Derivative liabilities	0	0
Southern California Gas Company [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	9	6
Total Liabilities Measured at Fair Value	8	6
Southern California Gas Company [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 assets	9	1
Effect of netting and allocation of collateral	0	5
Derivative liabilities	8	6
Southern California Gas Company [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	0	0
Total Liabilities Measured at Fair Value	0	0
Southern California Gas Company [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 assets	0	0
Effect of netting and allocation of collateral	0	0
Derivative liabilities	$ 0	$ 0