SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - EARNINGS (LOSSES) PER COMMON SHARE COMPUTATIONS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Income from continuing operations, net of income tax									$ 2,255	$ 1,999	$ 938
Earnings attributable to noncontrolling interests									(162)	(129)	(44)
Preferred dividends									(168)	(142)	(125)
Preferred dividends of subsidiary									(1)	(1)	(1)
Earnings from continuing operations attributable to common shares									1,924	1,727	768
Income from discontinued operations, net of income tax	$ 0	$ (7)	$ 1,777	$ 80	$ 71	$ 256	$ 78	$ (42)	1,850	363	188
Earnings attributable to noncontrolling interests									(10)	(35)	(32)
Earnings (losses) from discontinued operations attributable to common shares									1,840	328	156
Earnings attributable to common shares									3,764	2,055	924
Earnings attributable to common shares, diluted									$ 3,764	$ 2,055	$ 924
Weighted-average common shares outstanding for basic EPS (in shares)	289,000	289,500	293,100	292,800	284,600	277,400	275,000	274,700	291,077	277,904	268,072
Dilutive effect of stock options and RSUs (in shares)									1,175	1,585	919
Dilutive effect of common shares sold forward (in shares)									0	2,544	861
Weighted-average number of shares outstanding, diluted (in shares)	290,200	290,600	294,200	313,900	288,800	295,800	279,600	277,200	292,252	282,033	269,852
Earnings from continuing operations attributable to common shares	$ 1.43	$ 1.23	$ 1.58	$ 2.35	$ 1.36	$ 2.04	$ 1.03	$ 1.79	$ 6.61	$ 6.22	$ 2.86
Earnings (losses) from discontinued operations attributable to common shares	0	(0.02)	6.06	0.25	0.21	0.89	0.26	(0.19)	6.32	1.18	0.59
Basic earnings per common share (in shares)									12.93	7.40	3.45
Earnings from continuing operations (in dollars per share)	1.43	1.23	1.58	2.30	1.34	2.00	1.01	1.78	6.58	6.13	2.84
Earnings (losses) from discontinued operations (in dollars per share)	$ 0	$ (0.02)	$ 6.03	$ 0.23	$ 0.21	$ 0.84	$ 0.25	$ (0.19)	6.30	1.16	0.58
Diluted earnings per common share (in dollars per share)									$ 12.88	$ 7.29	$ 3.42
Fully vested RSUs included in the computation of EPS									537	617	641