SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - COMMON STOCK ACTIVITY (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
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	273,769,513	251,358,977	250,152,514
Shares issued under forward sale agreements	16,906,185	21,175,473	0
RSUs vesting	463,012	509,042	362,022
Stock options exercised	52,540	138,861	164,454
Savings plan issuance	475,774	553,036	567,428
Common stock investment plan	199,253	231,242	254,047
Issuance of RSUs held in our Deferred Compensation Plan	59,470	3,357	7,811
Shares repurchased	(212,822)	(200,475)	(149,299)
Common shares outstanding, December 31	291,712,925	273,769,513	251,358,977