ACQUISTION AND DIVESTITURE ACTIVITY - ASSETS HELD FOR SALE (Details) - Sempra Mexico [Member] - TdM [Member] $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended
	Feb. 29, 2016 MW	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generating capacity (in mw) | MW	625
Other than temporary impairment in investment		$ 71	$ 131
Other than temporary impairment in investment, net of tax			111
Deferred tax expense		0	$ 31	$ 32	$ 8
Disposal Group Held-for-sale [Member]
Assets Held for Sale, Assets [Abstract]
Inventories		10			10
Other current assets		25			25
Property, plant and equipment, net		55			55
Other noncurrent assets		27			27
Total assets held for sale		117			117
Assets Held for Sale, Liabilities [Abstract]
Accounts payable		5			5
Current liabilities		5			5
Asset retirement obligations		5			5
Other noncurrent liabilities		32			32
Total liabilities held for sale		$ 47			$ 47