OTHER FINANCIAL DATA - SHAREHOLDER'S EQUITY AND NONCONTROLLING INTEREST (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				$ 15,241,000,000	[1]	$ 12,579,000,000
Equity, beginning of period	[1]			12,951,000,000
Cumulative-effect adjustment from change in accounting principle			$ 107,000,000			107,000,000
Comprehensive income (loss)				888,000,000		1,050,000,000
Preferred dividends of subsidiary		$ 0	0	(1,000,000)		(1,000,000)
Share-based compensation expense				44,000,000		38,000,000
Common stock dividends declared				(619,000,000)		(565,000,000)
Issuances of common stock				77,000,000		80,000,000
Repurchases of common stock				(15,000,000)		(55,000,000)
Equity contributed by noncontrolling interest				2,000,000		2,000,000
Distributions to noncontrolling interests				(115,000,000)		(44,000,000)
Equity, end of period		15,502,000,000	13,191,000,000	15,502,000,000		13,191,000,000
Equity, end of period		13,265,000,000		13,265,000,000
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				12,951,000,000		11,809,000,000
Cumulative-effect adjustment from change in accounting principle			107,000,000			107,000,000
Comprehensive income (loss)				828,000,000		933,000,000
Preferred dividends of subsidiary				(1,000,000)		(1,000,000)
Share-based compensation expense				44,000,000		38,000,000
Common stock dividends declared				(619,000,000)		(565,000,000)
Issuances of common stock				77,000,000		80,000,000
Repurchases of common stock				(15,000,000)		(55,000,000)
Equity contributed by noncontrolling interest				0		0
Distributions to noncontrolling interests				0		0
Equity, end of period		13,265,000,000	12,346,000,000	13,265,000,000		12,346,000,000
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				2,290,000,000		770,000,000
Cumulative-effect adjustment from change in accounting principle			0			0
Comprehensive income (loss)				60,000,000		117,000,000
Preferred dividends of subsidiary				0		0
Share-based compensation expense				0		0
Common stock dividends declared				0		0
Issuances of common stock				0		0
Repurchases of common stock				0		0
Equity contributed by noncontrolling interest				2,000,000		2,000,000
Distributions to noncontrolling interests				(115,000,000)		(44,000,000)
Equity, end of period		2,237,000,000	845,000,000	2,237,000,000		845,000,000
San Diego Gas and Electric Company [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				5,678,000,000	[1]	5,276,000,000
Equity, beginning of period	[1]			5,641,000,000
Cumulative-effect adjustment from change in accounting principle			23,000,000			23,000,000
Comprehensive income (loss)				299,000,000		422,000,000
Common stock dividends declared				(450,000,000)		(175,000,000)
Equity contributed by noncontrolling interest				1,000,000		1,000,000
Distributions to noncontrolling interests				(25,000,000)		(7,000,000)
Equity, end of period		5,503,000,000	5,540,000,000	5,503,000,000		5,540,000,000
Equity, end of period		5,468,000,000		5,468,000,000
San Diego Gas and Electric Company [Member] | Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				5,641,000,000		5,223,000,000
Cumulative-effect adjustment from change in accounting principle			23,000,000			23,000,000
Comprehensive income (loss)				277,000,000		419,000,000
Common stock dividends declared				(450,000,000)		(175,000,000)
Equity contributed by noncontrolling interest				0		0
Distributions to noncontrolling interests				0		0
Equity, end of period		5,468,000,000	5,490,000,000	5,468,000,000		5,490,000,000
San Diego Gas and Electric Company [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				37,000,000		53,000,000
Cumulative-effect adjustment from change in accounting principle			0			0
Comprehensive income (loss)				22,000,000		3,000,000
Common stock dividends declared				0		0
Equity contributed by noncontrolling interest				1,000,000		1,000,000
Distributions to noncontrolling interests				(25,000,000)		(7,000,000)
Equity, end of period		35,000,000	50,000,000	35,000,000		50,000,000
Southern California Gas Company [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				3,510,000,000	[1]	3,149,000,000
Cumulative-effect adjustment from change in accounting principle			15,000,000			15,000,000
Comprehensive income (loss)				270,000,000		200,000,000
Preferred stock dividends declared		0	0	(1,000,000)		(1,000,000)
Equity, end of period		$ 3,779,000,000	$ 3,363,000,000	$ 3,779,000,000		$ 3,363,000,000

[1] Derived from audited financial statements.