FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	$ 499	$ 508
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	57	52
Nuclear decommissioning trusts - Municipal bonds	263	206
Nuclear decommissioning trusts - Other securities	199	141
Nuclear decommissioning trusts - Total debt securities	519	399
Nuclear decommissioning trusts - Netting	0	0
Total nuclear decommissioning trusts	1,018	907
Derivative asset netting	27	41
Total	1,280	1,072
Derivative liability netting	(25)	(35)
Total	395	441
Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	131	9
Derivative asset netting	0	0
Derivative liabilities	209	252
Derivative liability netting	0	0
Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	29	24
Derivative asset netting	10	9
Derivative liabilities	6	10
Derivative liability netting	0	(17)
Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	102	132
Derivative asset netting	17	32
Derivative liabilities	180	179
Derivative liability netting	(25)	(18)
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	494	508
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	49	36
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	49	36
Total nuclear decommissioning trusts	543	544
Total	550	545
Total	28	35
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	7	0
Derivative liabilities	3	16
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
Derivative liabilities	25	19
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	5	0
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	8	16
Nuclear decommissioning trusts - Municipal bonds	263	206
Nuclear decommissioning trusts - Other securities	199	141
Nuclear decommissioning trusts - Total debt securities	470	363
Total nuclear decommissioning trusts	475	363
Total	619	390
Total	218	271
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	131	9
Derivative liabilities	209	252
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	12	15
Derivative liabilities	3	11
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	1	3
Derivative liabilities	6	8
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	84	96
Total	174	170
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
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	84	96
Derivative liabilities	174	170
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	499	508
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	57	52
Nuclear decommissioning trusts - Municipal bonds	263	206
Nuclear decommissioning trusts - Other securities	199	141
Nuclear decommissioning trusts - Total debt securities	519	399
Nuclear decommissioning trusts - Netting	0	0
Total nuclear decommissioning trusts	1,018	907
Derivative asset netting	16	31
Total	1,118	1,037
Derivative liability netting	(25)	(16)
Total	199	203
San Diego Gas and Electric Company [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		1
Derivative asset netting		1
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	100	129
Derivative asset netting	16	30
Derivative liabilities	179	178
Derivative liability netting	(25)	(16)
San Diego Gas and Electric Company [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	20	25
Derivative liability netting	0	0
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	494	508
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	49	36
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	49	36
Total nuclear decommissioning trusts	543	544
Total	543	545
Total	25	17
San Diego Gas and Electric Company [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 assets		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	0	1
Derivative liabilities	25	17
San Diego Gas and Electric Company [Member] | Level 1 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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	5	0
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	8	16
Nuclear decommissioning trusts - Municipal bonds	263	206
Nuclear decommissioning trusts - Other securities	199	141
Nuclear decommissioning trusts - Total debt securities	470	363
Total nuclear decommissioning trusts	475	363
Total	475	365
Total	25	32
San Diego Gas and Electric Company [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 assets		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	0	2
Derivative liabilities	5	7
San Diego Gas and Electric Company [Member] | Level 2 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	20	25
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	84	96
Total	174	170
San Diego Gas and Electric Company [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 assets		0
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	84	96
Derivative liabilities	174	170
San Diego Gas and Electric Company [Member] | Level 3 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Southern California Gas Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset netting	2	3
Total	3	4
Derivative liability netting	0	(2)
Total	1	1
Southern California Gas Company [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1	1
Derivative asset netting	1	1
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	2	3
Derivative asset netting	1	2
Derivative liabilities	1	1
Derivative liability netting	0	(2)
Southern California Gas Company [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Total	0	2
Southern California Gas Company [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 assets	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	0
Derivative liabilities	0	2
Southern California Gas Company [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	1	1
Total	1	1
Southern California Gas Company [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 assets	0	0
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	1	1
Derivative liabilities	1	1
Southern California Gas Company [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Total	0	0
Southern California Gas Company [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 assets	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
Derivative liabilities	$ 0	$ 0