SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - COMMON STOCK OFFERINGS (Details) - USD ($)			1 Months Ended		3 Months Ended					12 Months Ended			18 Months Ended	21 Months Ended
	Aug. 04, 2020	Jul. 01, 2020	Jul. 31, 2018	Jan. 31, 2018	Dec. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Sep. 30, 2019	Jul. 06, 2020	Sep. 11, 2007
Shares issued (in shares)										0	16,906,185	21,175,473
Issuances of common stock, net										$ 11,000,000	$ 1,830,000,000	$ 2,272,000,000
Common Stock [Member]
Stock repurchase program, authorized amount															$ 2,000,000,000	$ 2,000,000,000
Number of shares authorized to be repurchased (in shares)															25,000,000	40,000,000
ASR program, amount prepaid		$ 500,000,000
Common shares repurchased	4,089,375
Common shares repurchased, average price (in dollars per share)	$ 122.27
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													$ 1,200,000,000	$ 2,800,000,000
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							$ 164,000,000		$ 367,000,000
Payments of stock issuance costs							$ 3,000,000		$ 8,000,000
Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Shares issued (in shares)					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					$ 1,066,000,000	$ 728,000,000		$ 800,000,000	$ 900,000,000
Payments of stock issuance costs					$ 18,000,000	$ 13,000,000		$ 14,000,000	$ 16,000,000
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