GENERAL INFORMATION AND OTHER FINANCIAL DATA - SHAREHOLDER'S EQUITY AND NONCONTROLLING INTEREST (Details) - USD ($)					1 Months Ended		3 Months Ended
		May 07, 2018	Mar. 08, 2018	Jan. 09, 2018	Jan. 31, 2018		Mar. 31, 2018		Mar. 31, 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											$ (1,000,000)
Comprehensive income (loss)							457,000,000		515,000,000
Share-based compensation expense							15,000,000		10,000,000
Mandatory convertible preferred stock dividends declared							(28,000,000)
Common stock dividends declared							(236,000,000)		(206,000,000)
Issuances of mandatory convertible preferred stock							1,693,000,000
Issuances of common stock							1,291,000,000		30,000,000
Repurchases of common stock							(19,000,000)		(14,000,000)
Distributions to noncontrolling interests							(7,000,000)		(7,000,000)
Equity, end of period							18,305,000,000		15,569,000,000
Equity, end of period							15,844,000,000
Proceeds from issuance							1,693,000,000		0	[2]
Proceeds from issuance							1,278,000,000		17,000,000	[2]
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											(1,000,000)
Comprehensive income (loss)							459,000,000		493,000,000
Share-based compensation expense							15,000,000		10,000,000
Mandatory convertible preferred stock dividends declared							(28,000,000)
Common stock dividends declared							(236,000,000)		(206,000,000)
Issuances of mandatory convertible preferred stock							1,693,000,000
Issuances of common stock							1,291,000,000		30,000,000
Repurchases of common stock							(19,000,000)		(14,000,000)
Distributions to noncontrolling interests							0		0
Equity, end of period							15,844,000,000		13,264,000,000
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											$ 0
Comprehensive income (loss)							(2,000,000)		22,000,000
Share-based compensation expense							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
Distributions to noncontrolling interests							(7,000,000)		(7,000,000)
Equity, end of period							2,461,000,000		2,305,000,000
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued			8,556,630	26,869,158
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)				$ 105.074
Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Underwriting discount			$ 16,000,000
Proceeds from issuance			$ 900,000,000
Forward sales price (in usd per share)			$ 105.1816
Sempra Energy [Member] | Convertible 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] | Convertible 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 income (loss)							173,000,000		160,000,000
Common stock dividends declared									(175,000,000)
Distributions to noncontrolling interests							(1,000,000)		(3,000,000)
Equity, end of period							5,798,000,000		5,660,000,000
Equity, end of period							5,768,000,000
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 income (loss)							170,000,000		155,000,000
Common stock dividends declared									(175,000,000)
Distributions to noncontrolling interests							0		0
Equity, end of period							5,768,000,000		5,621,000,000
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 income (loss)							3,000,000		5,000,000
Common stock dividends declared									0
Distributions to noncontrolling interests							(1,000,000)		(3,000,000)
Equity, end of period							30,000,000		39,000,000
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 income (loss)							225,000,000		203,000,000
Equity, end of period							$ 4,132,000,000		$ 3,713,000,000
Subsequent Event [Member] | Settlement of Forward Sale Contracts [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issuable under forward contracts		14,807,856

[1] Derived from audited financial statements.

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