ACQUISTION AND DIVESTITURE ACTIVITY - ASSETS HELD FOR SALE (Details) - Sempra Mexico [Member] - TdM [Member] $ in Millions	1 Months Ended	3 Months Ended
	Feb. 29, 2016 MW	Mar. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generating capacity (in mw) | MW	625
Deferred tax expense		$ 5
Disposal Group Held-for-sale [Member]
Assets Held for Sale, Assets [Abstract]
Inventories			$ 10
Other current assets			64
Property, plant and equipment, net			55
Other noncurrent assets			6
Total assets held for sale			135
Assets Held for Sale, Liabilities [Abstract]
Accounts payable			2
Current liabilities			38
Asset retirement obligations			5
Other noncurrent liabilities			7
Total liabilities held for sale			$ 52