FAIR VALUE MEASUREMENTS - RECURRING FAIR VALUE MEASURES (Details) - USD ($)	Sep. 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	$ 6,000,000
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear decommissioning trusts - equity securities	470,000,000	$ 411,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	51,000,000	53,000,000
Nuclear decommissioning trusts - Municipal bonds	291,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	578,000,000	556,000,000
Total nuclear decommissioning trusts	1,048,000,000	967,000,000
Total Assets Measured at Fair Value	1,364,000,000	1,334,000,000
Total Liabilities Measured at Fair Value	266,000,000	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	9,000,000	2,000,000
Derivative liabilities	169,000,000	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	12,000,000	24,000,000
Effect of netting and allocation of collateral	18,000,000	19,000,000
Derivative liabilities	18,000,000	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	260,000,000	289,000,000
Effect of netting and allocation of collateral	17,000,000	33,000,000
Derivative liabilities	94,000,000	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	465,000,000	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	504,000,000	450,000,000
Total Assets Measured at Fair Value	534,000,000	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	18,000,000	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	1,000,000	2,000,000
Effect of netting and allocation of collateral	11,000,000	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	12,000,000	10,000,000
Nuclear decommissioning trusts - Municipal bonds	291,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	539,000,000	513,000,000
Total nuclear decommissioning trusts	544,000,000	517,000,000
Total Assets Measured at Fair Value	571,000,000	552,000,000
Total Liabilities Measured at Fair Value	192,000,000	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	9,000,000	2,000,000
Derivative liabilities	169,000,000	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	12,000,000	24,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	18,000,000	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	6,000,000	9,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	5,000,000	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	259,000,000	283,000,000
Total Liabilities Measured at Fair Value	74,000,000	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	253,000,000	278,000,000
Effect of netting and allocation of collateral	6,000,000	5,000,000
Derivative liabilities	74,000,000	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	470,000,000	411,000,000
Nuclear decommissioning trusts - Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	51,000,000	53,000,000
Nuclear decommissioning trusts - Municipal bonds	291,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	578,000,000	556,000,000
Total nuclear decommissioning trusts	1,048,000,000	967,000,000
Total Assets Measured at Fair Value	1,316,000,000	1,280,000,000
Total Liabilities Measured at Fair Value	75,000,000	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	254,000,000	285,000,000
Effect of netting and allocation of collateral	14,000,000	28,000,000
Derivative liabilities	90,000,000	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	465,000,000	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	504,000,000	450,000,000
Total Assets Measured at Fair Value	512,000,000	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	8,000,000	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	12,000,000	10,000,000
Nuclear decommissioning trusts - Municipal bonds	291,000,000	269,000,000
Nuclear decommissioning trusts - Other securities	236,000,000	234,000,000
Nuclear decommissioning trusts - Total debt securities	539,000,000	513,000,000
Total nuclear decommissioning trusts	544,000,000	517,000,000
Total Assets Measured at Fair Value	545,000,000	523,000,000
Total Liabilities Measured at Fair Value	1,000,000	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	1,000,000	6,000,000
Effect of netting and allocation of collateral	0	0
Derivative liabilities	1,000,000	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	259,000,000	283,000,000
Total Liabilities Measured at Fair Value	74,000,000	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	253,000,000	278,000,000
Effect of netting and allocation of collateral	6,000,000	5,000,000
Derivative liabilities	74,000,000	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	9,000,000	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	6,000,000	4,000,000
Effect of netting and allocation of collateral	3,000,000	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	4,000,000	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	1,000,000	1,000,000
Effect of netting and allocation of collateral	3,000,000	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	5,000,000	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	5,000,000	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