ACQUISITION AND DIVESTITURE ACTIVITY - ASSETS HELD FOR SALE (Details) $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended
	Feb. 29, 2016 MW	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)		Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Assets Held for Sale [Line Items]
Impairment losses		$ 71	$ 21	[1]	$ 71	$ 22	[1],[2]
Sempra Mexico [Member] | TdM [Member]
Assets Held for Sale [Line Items]
Power generating capacity | MW	625
Impairment losses		71			71
Deferred tax expense (benefit) from the outside basis difference		(3)	$ 3		(8)	$ 32
Sempra Mexico [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | TdM [Member]
Assets Held for Sale, Assets [Abstract]
Inventories		10			10
Other current assets		19			19
Property, plant and equipment, net		55			55
Other noncurrent assets		25			25
Total assets held for sale		109			109
Assets Held for Sale, Liabilities [Abstract]
Accounts payable		11			11
Other current liabilities		4			4
Asset retirement obligations		5			5
Other noncurrent liabilities		27			27
Total liabilities held for sale		$ 47			$ 47

[1] As adjusted for the adoption of ASU 2016-09 as of January 1, 2016.

[2] As adjusted for the adoption of ASU 2016-09 as of January 1, 2016.