FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
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	$ 10,000,000
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	486,000,000	$ 496,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	50,000,000	54,000,000
Nuclear decommissioning trusts - Municipal bonds	258,000,000	250,000,000
Nuclear decommissioning trusts - Other securities	231,000,000	217,000,000
Nuclear decommissioning trusts - Total debt securities	539,000,000	521,000,000
Total nuclear decommissioning trusts	1,025,000,000	1,017,000,000
Total Assets Measured at Fair Value	1,227,000,000	1,188,000,000
Total LIabilities Measured at Fair Value	262,000,000	384,000,000
Recurring [Member] | Interest rate and foreign exchange instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	45,000,000	7,000,000
Derivative liabilities	132,000,000	217,000,000
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	11,000,000	17,000,000
Effect of netting and allocation of collateral	11,000,000	2,000,000
Derivative liabilities	12,000,000	6,000,000
Recurring [Member] | Commodity contracts subject to rate recovery [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	106,000,000	128,000,000
Effect of netting and allocation of collateral	29,000,000	17,000,000
Derivative liabilities	121,000,000	184,000,000
Effect of netting and allocation of collateral	(3,000,000)	(23,000,000)
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	482,000,000	491,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	40,000,000	45,000,000
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	40,000,000	45,000,000
Total nuclear decommissioning trusts	522,000,000	536,000,000
Total Assets Measured at Fair Value	561,000,000	555,000,000
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	4,000,000	5,000,000
Effect of netting and allocation of collateral	11,000,000	2,000,000
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	0
Effect of netting and allocation of collateral	24,000,000	12,000,000
Derivative liabilities	3,000,000	23,000,000
Effect of netting and allocation of collateral	(3,000,000)	(23,000,000)
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	4,000,000	5,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	10,000,000	9,000,000
Nuclear decommissioning trusts - Municipal bonds	258,000,000	250,000,000
Nuclear decommissioning trusts - Other securities	231,000,000	217,000,000
Nuclear decommissioning trusts - Total debt securities	499,000,000	476,000,000
Total nuclear decommissioning trusts	503,000,000	481,000,000
Total Assets Measured at Fair Value	560,000,000	502,000,000
Total LIabilities Measured at Fair Value	149,000,000	230,000,000
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	45,000,000	7,000,000
Derivative liabilities	132,000,000	217,000,000
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	7,000,000	12,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	12,000,000	6,000,000
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	5,000,000	2,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	5,000,000	7,000,000
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	106,000,000	131,000,000
Total LIabilities Measured at Fair Value	113,000,000	154,000,000
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	101,000,000	126,000,000
Effect of netting and allocation of collateral	5,000,000	5,000,000
Derivative liabilities	113,000,000	154,000,000
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	486,000,000	496,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	50,000,000	54,000,000
Nuclear decommissioning trusts - Municipal bonds	258,000,000	250,000,000
Nuclear decommissioning trusts - Other securities	231,000,000	217,000,000
Nuclear decommissioning trusts - Total debt securities	539,000,000	521,000,000
Total nuclear decommissioning trusts	1,025,000,000	1,017,000,000
Total Assets Measured at Fair Value	1,154,000,000	1,159,000,000
Total LIabilities Measured at Fair Value	117,000,000	172,000,000
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	103,000,000	126,000,000
Effect of netting and allocation of collateral	26,000,000	16,000,000
Derivative liabilities	116,000,000	182,000,000
Effect of netting and allocation of collateral	(3,000,000)	(23,000,000)
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	4,000,000	13,000,000
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	482,000,000	491,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	40,000,000	45,000,000
Nuclear decommissioning trusts - Municipal bonds	0	0
Nuclear decommissioning trusts - Other securities	0	0
Nuclear decommissioning trusts - Total debt securities	40,000,000	45,000,000
Total nuclear decommissioning trusts	522,000,000	536,000,000
Total Assets Measured at Fair Value	543,000,000	547,000,000
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	0
Effect of netting and allocation of collateral	21,000,000	11,000,000
Derivative liabilities	3,000,000	23,000,000
Effect of netting and allocation of collateral	(3,000,000)	(23,000,000)
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	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	4,000,000	5,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	10,000,000	9,000,000
Nuclear decommissioning trusts - Municipal bonds	258,000,000	250,000,000
Nuclear decommissioning trusts - Other securities	231,000,000	217,000,000
Nuclear decommissioning trusts - Total debt securities	499,000,000	476,000,000
Total nuclear decommissioning trusts	503,000,000	481,000,000
Total Assets Measured at Fair Value	505,000,000	481,000,000
Total LIabilities Measured at Fair Value	4,000,000	18,000,000
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	0
Effect of netting and allocation of collateral	0	0
Derivative liabilities	0	5,000,000
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	4,000,000	13,000,000
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	106,000,000	131,000,000
Total LIabilities Measured at Fair Value	113,000,000	154,000,000
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	101,000,000	126,000,000
Effect of netting and allocation of collateral	5,000,000	5,000,000
Derivative liabilities	113,000,000	154,000,000
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	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	6,000,000	3,000,000
Total LIabilities Measured at Fair Value	5,000,000	2,000,000
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	3,000,000	2,000,000
Effect of netting and allocation of collateral	3,000,000	1,000,000
Derivative liabilities	5,000,000	2,000,000
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	3,000,000	1,000,000
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	0
Effect of netting and allocation of collateral	3,000,000	1,000,000
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	3,000,000	2,000,000
Total LIabilities Measured at Fair Value	5,000,000	2,000,000
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	3,000,000	2,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	5,000,000	2,000,000
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
Disposal Group Held-for-sale [Member] | Sempra Renewables [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 3,000,000