SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - EARNINGS (LOSSES) PER COMMON SHARE COMPUTATIONS (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Income from continuing operations, net of income tax									$ 1,999	$ 938	$ 382
Earnings attributable to noncontrolling interests									(129)	(44)	(67)
Mandatory convertible preferred stock dividends									(142)	(125)	0
Preferred dividends of subsidiary									(1)	(1)	(1)
Earnings from continuing operations attributable to common shares									1,727	768	314
Income (loss) from discontinued operations, net of income tax									363	188	(31)
Earnings attributable to noncontrolling interests									(35)	(32)	(27)
Earnings (losses) from discontinued operations attributable to common shares	$ 71	$ 256	$ 78	$ (42)	$ 51	$ 54	$ 55	$ 28	328	156	(58)
Earnings attributable to common shares									$ 2,055	$ 924	$ 256
Weighted-average common shares outstanding for basic EPS (in shares)	284,600,000	277,400,000	275,000,000.0	274,700,000	274,300,000	273,900,000	265,800,000	257,900,000	277,904,000	268,072,000	251,545,000
Dilutive effect of stock options and RSUs (in shares)									1,585,000	919,000	755,000
Dilutive effect of common shares sold forward (in shares)									2,544,000	861,000	0
Weighted-average number of shares outstanding, diluted (in shares)	288,800,000	295,800,000	279,600,000	277,200,000	296,400,000	275,900,000	265,800,000	259,500,000	282,033,000	269,852,000	252,300,000
Earnings from continuing operations attributable to common shares	$ 1.36	$ 2.04	$ 1.03	$ 1.79	$ 3.00	$ 0.83	$ (2.29)	$ 1.26	$ 6.22	$ 2.86	$ 1.25
Earnings (losses) from discontinued operations attributable to common shares									1.18	0.59	(0.23)
Basic earnings per common share (in shares)	0.21	0.89	0.26	(0.19)	0.15	0.17	0.18	0.08	7.40	3.45	1.02
Earnings from continuing operations (in dollars per share)	1.34	2.00	1.01	1.78	2.89	0.82	(2.29)	1.25	6.13	2.84	1.24
Earnings (losses) from discontinued operations (in dollars per share)									1.16	0.58	(0.23)
Diluted earnings per common share (in dollars per share)	$ 0.21	$ 0.84	$ 0.25	$ (0.19)	$ 0.14	$ 0.17	$ 0.18	$ 0.08	$ 7.29	$ 3.42	$ 1.01
Fully vested RSUs included in the computation of EPS									617	641	609