SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - COMMON STOCK OFFERINGS (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		3 Months Ended					12 Months Ended			18 Months Ended	21 Months Ended
	Mar. 08, 2018	Jul. 31, 2018	Jan. 31, 2018	Dec. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Sep. 30, 2019
Issuances of common stock, net									$ 1,830	$ 2,272	$ 47
Public Offering [Member] | Common Stock [Member]
Shares issued (in shares)		11,212,500	26,869,158
Price of shares issued (in dollars per share)		$ 113.75	$ 107.00
Price of shares issued net of underwriting discount (in dollars per share)		$ 111.87	$ 105.07
Issuances of common stock, net												$ 1,200	$ 2,800
Common Stock Forward Sales [Member] | Common Stock [Member]
Shares issued (in shares)		9,750,000	23,364,486
Over-Allotment Option [Member] | Common Stock [Member]
Shares issued (in shares)						1,462,500		3,504,672
Price of shares issued net of underwriting discount (in dollars per share)						$ 111.87		$ 105.07
Issuances of common stock, net						$ 164		$ 367
Payments of stock issuance costs						$ 3		$ 8
Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Shares issued (in shares)	8,556,630			9,750,000	7,156,185		7,651,671	8,556,630
Price of shares issued net of underwriting discount (in dollars per share)				$ 109.33	$ 101.74			$ 105.18	$ 109.33			$ 109.33	$ 101.74
Issuances of common stock, net	$ 900			$ 1,066	$ 728		$ 800	$ 900
Payments of stock issuance costs	$ 16			$ 18	$ 13		$ 14	$ 16
Minimum [Member] | Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Price of shares issued net of underwriting discount (in dollars per share)							$ 104.53
Maximum [Member] | Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Price of shares issued net of underwriting discount (in dollars per share)							$ 104.58