QUARTERLY FINANCIAL DATA (UNAUDITED) - NARRATIVE (Details) - USD ($) $ in Millions	1 Months Ended					3 Months Ended		12 Months Ended
	Jun. 30, 2017	May 31, 2017	Sep. 30, 2016	May 31, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015	[1]
Significant Items Affecting Quarterly Results [Line Items]
Total increase in income tax expense due to tax cuts and jobs act								$ 870
Write-off of wildfire regulatory asset								351	$ 0	[1]	$ 0
San Diego Gas and Electric Company [Member]
Significant Items Affecting Quarterly Results [Line Items]
Total increase in income tax expense due to tax cuts and jobs act								28
Write-off of wildfire regulatory asset								351	0	[1]	$ 0
Sempra LNG & Midstream [Member]
Significant Items Affecting Quarterly Results [Line Items]
Other than temporary impairment in investment					$ 44
Other than temporary impairment in investment, net of tax					$ 27
Loss on release of pipeline capacity				$ 206
Loss on release of pipeline capacity net of tax				$ 123
Proceeds from settlement		$ 47
Proceeds from settlement net of taxes		$ 28
IEnova Pipelines [Member] | Sempra Mexico [Member] | IEnova [Member]
Significant Items Affecting Quarterly Results [Line Items]
Gain on acquisition of remaining voting rights			$ 617						617
Gain on acquisition of remaining voting rights, net of tax			432						$ 432
Gain on acquisition of remaining voting rights, net of tax and noncontrolling interests			350
Termoelectrica de Mexicali [Member] | Sempra Mexico [Member]
Significant Items Affecting Quarterly Results [Line Items]
Other than temporary impairment in investment	$ 71		131			$ 71	$ 131
Other than temporary impairment in investment, net of tax			111				$ 111
Other than temporary impairment in investment, net of tax and noncontrolling interest	$ 47		$ 90
Loss from Catastrophes [Member] | San Diego Gas and Electric Company [Member]
Significant Items Affecting Quarterly Results [Line Items]
Write-off of wildfire regulatory asset								351
Write-off of wildfire regulatory asset net of tax								$ 208

[1] As adjusted for the retrospective adoption of ASU 2016-15 and ASU 2016-18, which we discuss in Note 2.