SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - GOODWILL (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 2,364,000,000	[1]	$ 819,000,000
Acquisition of businesses			1,590,000,000
Sale of business			(72,000,000)
Acquisition of business – measurement period adjustment	(13,000,000)
Foreign currency translation	46,000,000		27,000,000
Goodwill, ending balance	2,397,000,000		2,364,000,000	[1]
Sempra South American Utilities [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	749,000,000		722,000,000
Acquisition of businesses			0
Sale of business			0
Acquisition of business – measurement period adjustment	0
Foreign currency translation	46,000,000		27,000,000
Goodwill, ending balance	795,000,000		749,000,000
Sempra Mexico [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	1,615,000,000		25,000,000
Acquisition of businesses			1,590,000,000
Sale of business			0
Acquisition of business – measurement period adjustment	(13,000,000)
Foreign currency translation	0		0
Goodwill, ending balance	1,602,000,000		1,615,000,000
Sempra LNG & Midstream [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	0		72,000,000
Acquisition of businesses			0
Sale of business			(72,000,000)
Acquisition of business – measurement period adjustment	0
Foreign currency translation	0		0
Goodwill, ending balance	$ 0		$ 0

[1] Reflects reclassifications to conform to current year presentation, which we discuss in Note 1.