SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - COMMON STOCK ACTIVITY (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock par value (in dollars per share)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares outstanding, January 1	291,712,925	273,769,513	251,358,977
Shares issued under forward sale agreements	0	16,906,185	21,175,473
RSUs vesting	896,839	463,012	509,042
Stock options exercised	4,400	52,540	138,861
Savings plan issuance	201,431	475,774	553,036
Common stock investment plan	42,955	199,253	231,242
Issuance of RSUs held in our Deferred Compensation Plan	103,552	59,470	3,357
Shares repurchased	(4,491,858)	(212,822)	(200,475)
Common shares outstanding, December 31	288,470,244	291,712,925	273,769,513