GENERAL INFORMATION AND OTHER FINANCIAL DATA - INCOME TAXES (Details) - USD ($)	3 Months Ended				6 Months Ended			12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017		Dec. 31, 2017
Income Tax Expense And Effective Income Tax Rates Disclosure [Line Items]
Income tax (benefit) expense	$ (583,000,000)		$ 167,000,000	[1]	$ (294,000,000)	$ 462,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(1,109,000,000)		397,000,000	[1]	(442,000,000)	1,149,000,000	[1]
Equity (losses) earnings, before income tax	(189,000,000)		18,000,000		(184,000,000)	21,000,000
Pretax (loss) income	$ (1,298,000,000)		$ 415,000,000		$ (626,000,000)	$ 1,170,000,000
Effective income tax rate	45.00%		40.00%		47.00%	39.00%
Federal tax rate					21.00%			35.00%
TCJA provisional income tax expense	$ 25,000,000	$ 870,000,000
San Diego Gas and Electric Company [Member]
Income Tax Expense And Effective Income Tax Rates Disclosure [Line Items]
Income tax (benefit) expense	42,000,000		$ 54,000,000	[1]	$ 98,000,000	$ 144,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	188,000,000		207,000,000	[1]	413,000,000	454,000,000	[1]
Pretax (loss) income	$ 188,000,000		$ 207,000,000		$ 413,000,000	$ 454,000,000
Effective income tax rate	22.00%		26.00%		24.00%	32.00%
TCJA increase (decrease) in deferred tax liabilities					$ (38,000,000)
Southern California Gas Company [Member]
Income Tax Expense And Effective Income Tax Rates Disclosure [Line Items]
Income tax (benefit) expense	$ 23,000,000		$ 19,000,000	[1]	82,000,000	$ 117,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	57,000,000		78,000,000	[1]	341,000,000	379,000,000	[1]
Pretax (loss) income	$ 57,000,000		$ 78,000,000		$ 341,000,000	$ 379,000,000
Effective income tax rate	40.00%		24.00%		24.00%	31.00%
TCJA increase (decrease) in deferred tax liabilities					$ 5,000,000

[1] As adjusted for the retrospective adoption of ASU 2017-07, which we discuss in Note 2, and a reclassification to conform to current year presentation, which we discuss in Note 1.