NEW ACCOUNTING STANDARDS - BALANCE SHEET IMPACT (Details) - USD ($) $ in Millions	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		$ 257	$ 202
Property, plant and equipment, net		36,796	36,503
Deferred income taxes		2,571	2,767
Other current liabilities		970	816
Deferred credits and other		1,529	1,602
Retained earnings		10,104	10,147
San Diego Gas and Electric Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		5	4
Property, plant and equipment, net		16,310	14,838
Deferred income taxes		1,616	1,530
Other current liabilities		141	147
Deferred credits and other		488	544
Retained earnings		4,687	4,268
Southern California Gas Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		31	48
Property, plant and equipment, net		12,439	11,406
Deferred income taxes		1,177	995
Other current liabilities		217	137
Deferred credits and other		330	345
Retained earnings		$ 3,390	$ 3,040
Scenario, Forecast [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets	$ (68)
Property, plant and equipment, net	(147)
Right-of-use assets – operating leases	623
Deferred income taxes	(3)
Other current liabilities	81
Long-term debt	(138)
Deferred credits and other	445
Retained earnings	17
Scenario, Forecast [Member] | San Diego Gas and Electric Company [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets	0
Property, plant and equipment, net	0
Right-of-use assets – operating leases	130
Deferred income taxes	0
Other current liabilities	20
Long-term debt	0
Deferred credits and other	110
Retained earnings	0
Scenario, Forecast [Member] | Southern California Gas Company [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets	0
Property, plant and equipment, net	0
Right-of-use assets – operating leases	116
Deferred income taxes	0
Other current liabilities	23
Long-term debt	0
Deferred credits and other	93
Retained earnings	$ 0