CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Regulated and Unregulated Operating Revenue [Abstract]
Utilities	$ 9,776	$ 9,261		$ 9,254
Energy-related businesses	1,431	922		977
Total revenues	11,207	10,183		10,231
Utilities [Abstract]
Cost of electric fuel and purchased power	(2,281)	(2,188)		(2,136)
Cost of natural gas	(1,190)	(1,067)		(1,134)
Energy-related businesses [Abstract]
Cost of natural gas, electric fuel and purchased power	(339)	(277)		(335)
Other cost of sales	(24)	(322)		(148)
Operation and maintenance	(3,117)	(2,970)		(2,886)
Depreciation and amortization	(1,490)	(1,312)	[1]	(1,250)	[1]
Franchise fees and other taxes	(436)	(426)		(423)
Write-off of wildfire regulatory asset	(351)	0	[1]	0	[1]
Impairment losses	(72)	(153)	[1]	(9)	[1]
Plant closure adjustment	0	0		26
Gain on sale of assets	3	134		70
Operating expenses
Impairment losses	72	153	[1]	9	[1]
Write-off of wildfire regulatory asset	351	0	[1]	0	[1]
Equity earnings, before income tax	34	6		104
Remeasurement of equity method investment	0	617		0
Other income, net	254	132		126
Interest income	46	26		29
Interest expense	(659)	(553)		(561)
Income before income taxes	1,585	1,830		1,704
Income tax (expense) benefit	(1,276)	(389)		(341)
Equity earnings, net of income tax	42	78		85
Net income	351	1,519	[1]	1,448	[1]
(Earnings) losses attributable to noncontrolling interest	(94)	(148)		(98)
Preferred dividends of subsidiary	(1)	(1)		(1)
Net income/Earnings	$ 256	$ 1,370		$ 1,349
Earnings Per Share, Basic [Abstract]
Basic earnings per common share (in dollars per share)	$ 1.02	$ 5.48		$ 5.43
Weighted-average number of shares outstanding, basic	251,545	250,217		248,249
Earnings Per Share, Diluted [Abstract]
Diluted earnings per common share (in dollars per share)	$ 1.01	$ 5.46		$ 5.37
Weighted-average number of shares outstanding, diluted	252,300	251,155		250,923
San Diego Gas and Electric Company [Member]
Operating revenues
Electric	$ 3,935	$ 3,754		$ 3,719
Natural gas	541	499		500
Total operating revenues	4,476	4,253		4,219
Energy-related businesses [Abstract]
Write-off of wildfire regulatory asset	(351)	0	[1]	0	[1]
Operating expenses
Cost of electric fuel and purchased power	1,293	1,187		1,151
Cost of natural gas	164	127		153
Operation and maintenance	1,020	1,048		1,017
Depreciation and amortization	670	646	[1]	604	[1]
Franchise fees and other taxes	265	255		262
Write-off of wildfire regulatory asset	351	0	[1]	0	[1]
Plant closure adjustment	0	0	[1]	(26)	[1]
Total operating expenses	3,763	3,263		3,161
Operating income	713	990		1,058
Other income, net	66	50		36
Interest expense	(203)	(195)		(204)
Income before income taxes	576	845		890
Income tax (expense) benefit	(155)	(280)		(284)
Net income	421	565	[1]	606	[1]
(Earnings) losses attributable to noncontrolling interest	(14)	5		(19)
Earnings attributable to common shares	407	570		587
Southern California Gas Company [Member]
Operating revenues
Total operating revenues	3,785	3,471		3,489
Energy-related businesses [Abstract]
Impairment losses	0	(22)		(9)
Operating expenses
Cost of natural gas	1,025	891		921
Operation and maintenance	1,479	1,385		1,361
Depreciation and amortization	515	476		461
Franchise fees and other taxes	144	140		129
Impairment losses	0	22		9
Total operating expenses	3,163	2,914		2,881
Operating income	622	557		608
Other income, net	36	32		30
Interest income	1	1		4
Interest expense	(102)	(97)		(84)
Income before income taxes	557	493		558
Income tax (expense) benefit	(160)	(143)		(138)
Net income	397	350		420
Preferred dividend requirements	(1)	(1)		(1)
Earnings attributable to common shares	$ 396	$ 349		$ 419

[1] As adjusted for the retrospective adoption of ASU 2016-15 and ASU 2016-18, which we discuss in Note 2.