INCOME TAXES - EFFECTS OF THE TAX CUTS AND JOBS ACT OF 2017 (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Feb. 27, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
Decrease in net deferred income tax liabilities due to remeasurement		$ (2,220)
Increase in net regulatory liabilities from remeasurement of deferred tax income tax assets and liabilities		2,402
Income tax expense, related to remeasurement of deferred income tax assets and liabilities		182
Income tax expense related to deemed repatriation		328
U.S. state and non-U.S. withholding tax expense, related to expected future repatriation of foreign earnings		360
Total increase in income tax expense		$ 870
U.S. federal statutory income tax rate		35.00%	35.00%	35.00%
Foreign undistributed earnings		$ 4,000
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]
Decrease in net deferred income tax liabilities due to remeasurement		(1,400)
Increase in net regulatory liabilities from remeasurement of deferred tax income tax assets and liabilities		1,428
Income tax expense, related to remeasurement of deferred income tax assets and liabilities		28
Income tax expense related to deemed repatriation		0
U.S. state and non-U.S. withholding tax expense, related to expected future repatriation of foreign earnings		0
Total increase in income tax expense		$ 28
U.S. federal statutory income tax rate		35.00%	35.00%	35.00%
Southern California Gas Company [Member]
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
Decrease in net deferred income tax liabilities due to remeasurement		$ (972)
Increase in net regulatory liabilities from remeasurement of deferred tax income tax assets and liabilities		974
Income tax expense, related to remeasurement of deferred income tax assets and liabilities		2
Income tax expense related to deemed repatriation		0
U.S. state and non-U.S. withholding tax expense, related to expected future repatriation of foreign earnings		0
Total increase in income tax expense		$ 2
U.S. federal statutory income tax rate		35.00%	35.00%	35.00%
Subsequent Event [Member]
Schedule of Effect of Changes in Legislation of Income Tax (Expense) [Line Items]
U.S. federal statutory income tax rate	21.00%
U.S. federal statutory income tax rate on foreign earning held as cash and cash equivalents	15.50%
U.S. federal statutory income tax rate on foreign other accumulated earnings	8.00%