SEMPRA ENERGY - SHAREHOLDERS' EQUITY AND EARNINGS PER SHARE - EARNINGS PER SHARE COMPUTATIONS AND DIVIDENDS DECLARED (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings attributable to common shares									$ 924	$ 256	[1]	$ 1,370	[1]
Weighted-average common shares outstanding for basic EPS (in shares)	274,300,000	273,900,000	265,800,000	257,900,000	251,900,000	251,700,000	251,400,000	251,100,000	268,072,000	251,545,000	[1]	250,217,000	[1]
Dilutive effect of stock options, restricted stock awards and restricted stock units (in shares)									919,000	755,000		938,000
Dilutive effect of common shares sold forward (in shares)									861,000	0		0
Weighted-average number of shares outstanding, diluted (in shares)	296,400,000	275,900,000	265,800,000	259,500,000	251,900,000	253,400,000	252,800,000	252,200,000	269,852,000	252,300,000	[1]	251,155,000	[1]
Basic earnings per common share (in dollars per share)	$ 3.51	$ 1.22	$ (1.99)	$ 1.39	$ (1.80)	$ 0.41	$ 0.99	$ 1.80	$ 3.45	$ 1.02	[1]	$ 5.48	[1]
Diluted earnings per common share (in dollars per share)	$ 3.25	$ 1.21	$ (1.99)	$ 1.38	$ (1.80)	$ 0.41	$ 0.98	$ 1.79	$ 3.42	$ 1.01	[1]	$ 5.46	[1]
Fully vested RSUs included in the computation of EPS									641	609		568

[1] As adjusted for the retrospective adoption of ASU 2017-07, which we discuss in Note 2, and a reclassification to conform to current year presentation, which we discuss in Note 1.