FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - USD ($)	Mar. 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]
Investments at NAV	$ 7,000,000
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	459,000,000	$ 411,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	48,000,000	53,000,000
Nuclear decommissioning trusts - Municipal bonds	279,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	238,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	565,000,000	556,000,000
Total nuclear decommissioning trusts	1,024,000,000	967,000,000
Total Assets Measured at Fair Value	1,381,000,000	1,334,000,000
Total LIabilities Measured at Fair Value	265,000,000	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	12,000,000	2,000,000
Derivative liabilities	151,000,000	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	15,000,000	24,000,000
Effect of netting and allocation of collateral	25,000,000	19,000,000
Derivative liabilities	21,000,000	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	279,000,000	289,000,000
Effect of netting and allocation of collateral	26,000,000	33,000,000
Derivative liabilities	99,000,000	106,000,000
Effect of netting and allocation of collateral	(6,000,000)	(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	454,000,000	407,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	39,000,000	43,000,000
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	39,000,000	43,000,000
Total nuclear decommissioning trusts	493,000,000	450,000,000
Total Assets Measured at Fair Value	539,000,000	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	25,000,000	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	21,000,000	28,000,000
Derivative liabilities	6,000,000	2,000,000
Effect of netting and allocation of collateral	(6,000,000)	(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	9,000,000	10,000,000
Nuclear decommissioning trusts - Municipal bonds	279,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	238,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	526,000,000	513,000,000
Total nuclear decommissioning trusts	531,000,000	517,000,000
Total Assets Measured at Fair Value	566,000,000	552,000,000
Total LIabilities Measured at Fair Value	176,000,000	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	12,000,000	2,000,000
Derivative liabilities	151,000,000	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	15,000,000	24,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	21,000,000	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	4,000,000	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	276,000,000	283,000,000
Total LIabilities Measured at Fair Value	89,000,000	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	271,000,000	278,000,000
Effect of netting and allocation of collateral	5,000,000	5,000,000
Derivative liabilities	89,000,000	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	459,000,000	411,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	48,000,000	53,000,000
Nuclear decommissioning trusts - Municipal bonds	279,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	238,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	565,000,000	556,000,000
Total nuclear decommissioning trusts	1,024,000,000	967,000,000
Total Assets Measured at Fair Value	1,321,000,000	1,280,000,000
Total LIabilities Measured at Fair Value	89,000,000	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	272,000,000	285,000,000
Effect of netting and allocation of collateral	25,000,000	28,000,000
Derivative liabilities	95,000,000	101,000,000
Effect of netting and allocation of collateral	(6,000,000)	(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	454,000,000	407,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	39,000,000	43,000,000
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	39,000,000	43,000,000
Total nuclear decommissioning trusts	493,000,000	450,000,000
Total Assets Measured at Fair Value	513,000,000	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	20,000,000	23,000,000
Derivative liabilities	6,000,000	2,000,000
Effect of netting and allocation of collateral	(6,000,000)	(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	9,000,000	10,000,000
Nuclear decommissioning trusts - Municipal bonds	279,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	238,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	526,000,000	513,000,000
Total nuclear decommissioning trusts	531,000,000	517,000,000
Total Assets Measured at Fair Value	532,000,000	523,000,000
Total LIabilities Measured at Fair Value	0	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	1,000,000	6,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	0	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	276,000,000	283,000,000
Total LIabilities Measured at Fair Value	89,000,000	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	271,000,000	278,000,000
Effect of netting and allocation of collateral	5,000,000	5,000,000
Derivative liabilities	89,000,000	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	8,000,000	9,000,000
Total LIabilities Measured at Fair Value	4,000,000	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	7,000,000	4,000,000
Effect of netting and allocation of collateral	1,000,000	5,000,000
Derivative liabilities	4,000,000	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	7,000,000	3,000,000
Total LIabilities Measured at Fair Value	4,000,000	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	7,000,000	3,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	4,000,000	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