INCOME TAXES - EFFECTS OF THE TAX CUTS AND JOBS ACT OF 2017 (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
U.S. federal statutory income tax rate		21.00%	35.00%	35.00%
Income tax expense recognized in current period, related to remeasurement of deferred income tax assets and liabilities		$ 20
Income tax expense, related to remeasurement of deferred income tax assets and liabilities		49	$ 182
Increase in net regulatory liabilities from remeasurement of deferred tax income tax assets and liabilities		33	2,402
Decrease in net deferred income tax liabilities due to remeasurement		16	(2,220)
Income tax expense related to deemed repatriation		(8)	328
Foreign undistributed earnings	$ 4,000	3,700	4,000
Foreign earnings repatriated		338
U.S. state and non-U.S. withholding tax expense, related to expected future repatriation of foreign earnings		44	360
Total increase in income tax expense	$ 870	85	$ 870
Undistributed earnings of foreign subsidiaries considered to be indefinitely reinvested		$ 1,000
San Diego Gas and Electric Company [Member]
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
U.S. federal statutory income tax rate		21.00%	35.00%	35.00%
Income tax expense, related to remeasurement of deferred income tax assets and liabilities		$ 0	$ 28
Increase in net regulatory liabilities from remeasurement of deferred tax income tax assets and liabilities		38	1,428
Decrease in net deferred income tax liabilities due to remeasurement		(38)	(1,400)
Income tax expense related to deemed repatriation		0	0
U.S. state and non-U.S. withholding tax expense, related to expected future repatriation of foreign earnings		0	0
Total increase in income tax expense		$ 0	$ 28
Southern California Gas Company [Member]
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
U.S. federal statutory income tax rate		21.00%	35.00%	35.00%
Income tax expense, related to remeasurement of deferred income tax assets and liabilities		$ 0	$ 2
Increase in net regulatory liabilities from remeasurement of deferred tax income tax assets and liabilities		(5)	974
Decrease in net deferred income tax liabilities due to remeasurement		5	(972)
Income tax expense related to deemed repatriation		0	0
U.S. state and non-U.S. withholding tax expense, related to expected future repatriation of foreign earnings		0	0
Total increase in income tax expense		0	$ 2
U.S. Federal [Member]
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
Operating loss valuation allowance		$ 29