SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - COMMON STOCK ACTIVITY (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jan. 09, 2018	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Earnings Per Share [Abstract]
Common stock, shares authorized		750,000,000	750,000,000
Common stock par value (in dollars per share)		$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares outstanding, January 1		250,152,514	248,298,080		246,330,884
RSUs vesting		362,022	1,363,555		1,499,062
Stock options exercised		164,454	167,742		227,815
Savings plan issuance		567,428	653,607		652,631
Common stock investment plan		254,047	266,056		249,665
Issuance of RSUs held in our Deferred Compensation Plan		7,811	0		0
Shares repurchased		149,299	596,526		661,977
Common shares outstanding, December 31		251,358,977	250,152,514		248,298,080
Schedule of Capitalization, Equity [Line Items]
Issuances of common stock		$ 47	$ 51	[1]	$ 52	[1]
Subsequent Event [Member] | Public Offering [Member]
Schedule of Capitalization, Equity [Line Items]
Shares issued	23,364,486
Subsequent Event [Member] | Over-Allotment Option [Member]
Schedule of Capitalization, Equity [Line Items]
Shares issued	3,504,672
Issuances of common stock	$ 368

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