GENERAL INFORMATION AND OTHER FINANCIAL DATA - INVENTORIES (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Inventory [Line Items]
Natural gas	$ 169	$ 118
LNG	17	7
Materials and supplies	185	183
Inventory	371	308	[1]
San Diego Gas and Electric Company [Member]
Inventory [Line Items]
Natural gas	0	0
LNG	0	0
Materials and supplies	112	104
Inventory	112	104	[1]
Southern California Gas Company [Member]
Inventory [Line Items]
Natural gas	110	94
LNG	0	0
Materials and supplies	58	59
Inventory	$ 168	$ 153	[1]

[1] Derived from audited financial statements.