FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - USD ($)	Jun. 30, 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]
Investments at NAV	$ 5,000,000
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	467,000,000	$ 411,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	46,000,000	53,000,000
Nuclear decommissioning trusts - Municipal bonds	289,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	571,000,000	556,000,000
Total nuclear decommissioning trusts	1,038,000,000	967,000,000
Total Assets Measured at Fair Value	1,374,000,000	1,334,000,000
Total Liabilities Measured at Fair Value	275,000,000	288,000,000
Recurring [Member] | Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	21,000,000	2,000,000
Derivative liabilities	165,000,000	150,000,000
Recurring [Member] | Commodity contracts not subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	10,000,000	24,000,000
Effect of netting and allocation of collateral	19,000,000	19,000,000
Derivative liabilities	12,000,000	34,000,000
Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	270,000,000	289,000,000
Effect of netting and allocation of collateral	16,000,000	33,000,000
Derivative liabilities	113,000,000	106,000,000
Effect of netting and allocation of collateral	(15,000,000)	(2,000,000)
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	462,000,000	407,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	36,000,000	43,000,000
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	36,000,000	43,000,000
Total nuclear decommissioning trusts	498,000,000	450,000,000
Total Assets Measured at Fair Value	527,000,000	499,000,000
Total Liabilities Measured at Fair Value	0	0
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 assets	0	0
Derivative liabilities	0	0
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 assets	0	0
Effect of netting and allocation of collateral	19,000,000	19,000,000
Derivative liabilities	0	0
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 assets	0	2,000,000
Effect of netting and allocation of collateral	10,000,000	28,000,000
Derivative liabilities	15,000,000	2,000,000
Effect of netting and allocation of collateral	(15,000,000)	(2,000,000)
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	5,000,000	4,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	10,000,000	10,000,000
Nuclear decommissioning trusts - Municipal bonds	289,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	535,000,000	513,000,000
Total nuclear decommissioning trusts	540,000,000	517,000,000
Total Assets Measured at Fair Value	579,000,000	552,000,000
Total Liabilities Measured at Fair Value	189,000,000	189,000,000
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 assets	21,000,000	2,000,000
Derivative liabilities	165,000,000	150,000,000
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 assets	10,000,000	24,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	12,000,000	34,000,000
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 assets	8,000,000	9,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	12,000,000	5,000,000
Effect of netting and allocation of collateral	0	0
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 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	268,000,000	283,000,000
Total Liabilities Measured at Fair Value	86,000,000	99,000,000
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 assets	0	0
Derivative liabilities	0	0
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 assets	0	0
Effect of netting and allocation of collateral	0	0
Derivative liabilities	0	0
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 assets	262,000,000	278,000,000
Effect of netting and allocation of collateral	6,000,000	5,000,000
Derivative liabilities	86,000,000	99,000,000
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	467,000,000	411,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	46,000,000	53,000,000
Nuclear decommissioning trusts - Municipal bonds	289,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	571,000,000	556,000,000
Total nuclear decommissioning trusts	1,038,000,000	967,000,000
Total Assets Measured at Fair Value	1,317,000,000	1,280,000,000
Total Liabilities Measured at Fair Value	96,000,000	100,000,000
San Diego Gas and Electric Company [Member] | Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	264,000,000	285,000,000
Effect of netting and allocation of collateral	15,000,000	28,000,000
Derivative liabilities	111,000,000	101,000,000
Effect of netting and allocation of collateral	(15,000,000)	(2,000,000)
San Diego Gas and Electric Company [Member] | Recurring [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		1,000,000
San Diego Gas and Electric Company [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	462,000,000	407,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	36,000,000	43,000,000
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	36,000,000	43,000,000
Total nuclear decommissioning trusts	498,000,000	450,000,000
Total Assets Measured at Fair Value	507,000,000	474,000,000
Total Liabilities Measured at Fair Value	0	0
San Diego Gas and Electric Company [Member] | 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 assets	0	1,000,000
Effect of netting and allocation of collateral	9,000,000	23,000,000
Derivative liabilities	15,000,000	2,000,000
Effect of netting and allocation of collateral	(15,000,000)	(2,000,000)
San Diego Gas and Electric Company [Member] | Recurring [Member] | Level 1 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0
San Diego Gas and Electric Company [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	5,000,000	4,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	10,000,000	10,000,000
Nuclear decommissioning trusts - Municipal bonds	289,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	535,000,000	513,000,000
Total nuclear decommissioning trusts	540,000,000	517,000,000
Total Assets Measured at Fair Value	542,000,000	523,000,000
Total Liabilities Measured at Fair Value	10,000,000	1,000,000
San Diego Gas and Electric Company [Member] | 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 assets	2,000,000	6,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	10,000,000	0
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Recurring [Member] | Level 2 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		1,000,000
San Diego Gas and Electric Company [Member] | 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 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	268,000,000	283,000,000
Total Liabilities Measured at Fair Value	86,000,000	99,000,000
San Diego Gas and Electric Company [Member] | 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 assets	262,000,000	278,000,000
Effect of netting and allocation of collateral	6,000,000	5,000,000
Derivative liabilities	86,000,000	99,000,000
Effect of netting and allocation of collateral	0	0
San Diego Gas and Electric Company [Member] | Recurring [Member] | Level 3 [Member] | Interest rate instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0
Southern California Gas Company [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	7,000,000	9,000,000
Total Liabilities Measured at Fair Value	2,000,000	5,000,000
Southern California Gas Company [Member] | Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	6,000,000	4,000,000
Effect of netting and allocation of collateral	1,000,000	5,000,000
Derivative liabilities	2,000,000	5,000,000
Southern California Gas Company [Member] | Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	1,000,000	6,000,000
Total Liabilities Measured at Fair Value	0	0
Southern California Gas Company [Member] | 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 assets	0	1,000,000
Effect of netting and allocation of collateral	1,000,000	5,000,000
Derivative liabilities	0	0
Southern California Gas Company [Member] | Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets Measured at Fair Value	6,000,000	3,000,000
Total Liabilities Measured at Fair Value	2,000,000	5,000,000
Southern California Gas Company [Member] | 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 assets	6,000,000	3,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	2,000,000	5,000,000
Southern California Gas Company [Member] | Recurring [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] | 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 assets	0	0
Effect of netting and allocation of collateral	0	0
Derivative liabilities	$ 0	$ 0