GENERAL INFORMATION AND OTHER FINANCIAL DATA - SHAREHOLDER'S EQUITY AND NONCONTROLLING INTEREST (Details) - USD ($)						1 Months Ended		3 Months Ended			6 Months Ended
		Aug. 06, 2018	Jul. 13, 2018	Mar. 08, 2018	Jan. 09, 2018	Jan. 31, 2018		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017		Jan. 01, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						$ 15,140,000,000	[1]				$ 15,140,000,000	[1]	$ 15,241,000,000
Equity, beginning of period	[1]					12,670,000,000					12,670,000,000
Cumulative-effect adjustment from change in accounting principle(2)															$ (1,000,000)
Comprehensive (loss) income											(131,000,000)		739,000,000
Share-based compensation expense											33,000,000		23,000,000
Preferred dividends of subsidiary								$ (1,000,000)	$ (1,000,000)	[2]	(1,000,000)		(1,000,000)	[2]
Mandatory convertible preferred stock dividends declared											(53,000,000)
Common stock dividends declared											(480,000,000)		(413,000,000)
Issuances of mandatory convertible preferred stock											1,693,000,000
Issuances of common stock											2,117,000,000		55,000,000
Repurchases of common stock											(20,000,000)		(14,000,000)
Equity contributed by noncontrolling interest											1,000,000		1,000,000
Distributions to noncontrolling interests											(18,000,000)		(26,000,000)
Purchase of noncontrolling interests											(1,000,000)
Sale of noncontrolling interests, net of offering costs											85,000,000
Equity, end of period								18,364,000,000	15,605,000,000		18,364,000,000		15,605,000,000
Equity, end of period								15,826,000,000			15,826,000,000
Proceeds from issuance											1,693,000,000		0	[3]
Proceeds from issuance											2,090,000,000		28,000,000	[3]
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						12,670,000,000					12,670,000,000		12,951,000,000
Cumulative-effect adjustment from change in accounting principle(2)															(1,000,000)
Comprehensive (loss) income											(132,000,000)		731,000,000
Share-based compensation expense											33,000,000		23,000,000
Preferred dividends of subsidiary											(1,000,000)		(1,000,000)
Mandatory convertible preferred stock dividends declared											(53,000,000)
Common stock dividends declared											(480,000,000)		(413,000,000)
Issuances of mandatory convertible preferred stock											1,693,000,000
Issuances of common stock											2,117,000,000		55,000,000
Repurchases of common stock											(20,000,000)		(14,000,000)
Equity contributed by noncontrolling interest											0		0
Distributions to noncontrolling interests											0		0
Purchase of noncontrolling interests											0
Sale of noncontrolling interests, net of offering costs											0
Equity, end of period								15,826,000,000	13,332,000,000		15,826,000,000		13,332,000,000
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						2,470,000,000					2,470,000,000		2,290,000,000
Cumulative-effect adjustment from change in accounting principle(2)															$ 0
Comprehensive (loss) income											1,000,000		8,000,000
Share-based compensation expense											0		0
Preferred dividends of subsidiary											0		0
Mandatory convertible preferred stock dividends declared											0
Common stock dividends declared											0		0
Issuances of mandatory convertible preferred stock											0
Issuances of common stock											0		0
Repurchases of common stock											0		0
Equity contributed by noncontrolling interest											1,000,000		1,000,000
Distributions to noncontrolling interests											(18,000,000)		(26,000,000)
Purchase of noncontrolling interests											(1,000,000)
Sale of noncontrolling interests, net of offering costs											85,000,000
Equity, end of period								$ 2,538,000,000	2,273,000,000		$ 2,538,000,000		2,273,000,000
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued				8,556,630	26,869,158			7,651,671			16,208,301
Over-Allotment Option [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued					3,504,672
Underwriting discount					$ 8,000,000
Proceeds from issuance					$ 367,000,000
Public Offering [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued					23,364,486
Shares issued (in usd per share)					$ 107.00
Shares issued net of underwriting discount (in usd per share)					$ 105.07
Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Underwriting discount								$ 14,000,000			$ 30,000,000
Proceeds from issuance				$ 900,000,000				$ 800,000,000			$ 1,700,000,000
Forward sales price (in usd per share)								$ 104.53			$ 105.18
Sempra Energy [Member] | Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued					17,250,000
Conversion price (in usd per share)					$ 100.00
Conversion price net of underwriting discount (in usd per share)					98.20
Liquidation price (in usd per share)					$ 100.00
Proceeds from issuance						1,690,000,000
Underwriting discount					$ 32,000,000
Sempra Energy [Member] | Over-Allotment Option [Member] | Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued					2,250,000
San Diego Gas and Electric Company [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						5,626,000,000	[1]				$ 5,626,000,000	[1]	5,678,000,000
Equity, beginning of period	[1]					5,598,000,000					5,598,000,000
Comprehensive (loss) income											320,000,000		314,000,000
Common stock dividends declared													(175,000,000)
Equity contributed by noncontrolling interest											1,000,000		1,000,000
Distributions to noncontrolling interests											(4,000,000)		(14,000,000)
Equity, end of period								$ 5,943,000,000	5,804,000,000		5,943,000,000		5,804,000,000
Equity, end of period								5,914,000,000			5,914,000,000
San Diego Gas and Electric Company [Member] | Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						5,598,000,000					5,598,000,000		5,641,000,000
Comprehensive (loss) income											316,000,000		304,000,000
Common stock dividends declared													(175,000,000)
Equity contributed by noncontrolling interest											0		0
Distributions to noncontrolling interests											0		0
Equity, end of period								5,914,000,000	5,770,000,000		5,914,000,000		5,770,000,000
San Diego Gas and Electric Company [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						28,000,000					28,000,000		37,000,000
Comprehensive (loss) income											4,000,000		10,000,000
Common stock dividends declared													0
Equity contributed by noncontrolling interest											1,000,000		1,000,000
Distributions to noncontrolling interests											(4,000,000)		(14,000,000)
Equity, end of period								29,000,000	34,000,000		29,000,000		34,000,000
Southern California Gas Company [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period						$ 3,907,000,000	[1]				3,907,000,000	[1]	3,510,000,000
Comprehensive (loss) income											260,000,000		263,000,000
Mandatory convertible preferred stock dividends declared								(1,000,000)	(1,000,000)	[2]	(1,000,000)		(1,000,000)	[2]
Equity, end of period								$ 4,166,000,000	$ 3,772,000,000		$ 4,166,000,000		$ 3,772,000,000
Subsequent Event [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued			11,212,500
Subsequent Event [Member] | Over-Allotment Option [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued			1,462,500
Proceeds from issuance			$ 163,600,000
Subsequent Event [Member] | Public Offering [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued			9,750,000
Shares issued (in usd per share)			$ 113.75
Shares issued net of underwriting discount (in usd per share)			$ 111.87
Proceeds from issuance			$ 163,600,000
Subsequent Event [Member] | Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issuable under forward contracts		16,906,185
Subsequent Event [Member] | Sempra Energy [Member] | Series B Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued			5,750,000
Stated rate of debt			6.75%
Conversion price (in usd per share)			$ 100.00
Conversion price net of underwriting discount (in usd per share)			98.35
Liquidation price (in usd per share)			$ 100
Proceeds from issuance			$ 565,500,000
Subsequent Event [Member] | Sempra Energy [Member] | Over-Allotment Option [Member] | Series B Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued			750,000

[1] Derived from audited financial statements.

[2] 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.

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