OTHER FINANCIAL DATA - SHAREHOLDER'S EQUITY AND NONCONTROLLING INTEREST (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015	Dec. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				$ 12,579,000,000	[1]	$ 12,100,000,000
Equity, beginning of period	[1]			11,809,000,000
Cumulative-effect adjustment from change in accounting principle							$ 107,000,000
Comprehensive income (loss)				1,050,000,000		773,000,000
Preferred dividends of subsidiary		$ 0	$ 0	(1,000,000)		(1,000,000)
Share-based compensation expense				38,000,000		39,000,000
Common stock dividends declared				(565,000,000)		(520,000,000)
Issuances of common stock				80,000,000		82,000,000
Repurchases of common stock				(55,000,000)		(74,000,000)
Tax benefit related to share-based compensation						56,000,000
Equity contributed by noncontrolling interests				2,000,000		1,000,000
Distributions to noncontrolling interests				(44,000,000)		(60,000,000)
Equity, end of period		13,191,000,000	12,396,000,000	13,191,000,000		12,396,000,000
Equity, end of period		12,346,000,000		12,346,000,000
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				11,809,000,000		11,326,000,000
Cumulative-effect adjustment from change in accounting principle							107,000,000
Comprehensive income (loss)				933,000,000		717,000,000
Preferred dividends of subsidiary				(1,000,000)		(1,000,000)
Share-based compensation expense				38,000,000		39,000,000
Common stock dividends declared				(565,000,000)		(520,000,000)
Issuances of common stock				80,000,000		82,000,000
Repurchases of common stock				(55,000,000)		(74,000,000)
Tax benefit related to share-based compensation						56,000,000
Equity contributed by noncontrolling interests				0		0
Distributions to noncontrolling interests				0		0
Equity, end of period		12,346,000,000	11,625,000,000	12,346,000,000		11,625,000,000
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				770,000,000		774,000,000
Cumulative-effect adjustment from change in accounting principle							0
Comprehensive income (loss)				117,000,000		56,000,000
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
Tax benefit related to share-based compensation						0
Equity contributed by noncontrolling interests				2,000,000		1,000,000
Distributions to noncontrolling interests				(44,000,000)		(60,000,000)
Equity, end of period		845,000,000	771,000,000	845,000,000		771,000,000
San Diego Gas and Electric Company [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				5,276,000,000	[1]	4,992,000,000
Equity, beginning of period	[1]			5,223,000,000
Cumulative-effect adjustment from change in accounting principle							23,000,000
Comprehensive income (loss)				422,000,000		463,000,000
Common stock dividends declared				(175,000,000)		(150,000,000)
Equity contributed by noncontrolling interests				1,000,000
Distributions to noncontrolling interests				(7,000,000)		(16,000,000)
Equity, end of period		5,540,000,000	5,289,000,000	5,540,000,000		5,289,000,000
Equity, end of period		5,490,000,000		5,490,000,000
San Diego Gas and Electric Company [Member] | Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				5,223,000,000		4,932,000,000
Cumulative-effect adjustment from change in accounting principle							23,000,000
Comprehensive income (loss)				419,000,000		443,000,000
Common stock dividends declared				(175,000,000)		(150,000,000)
Equity contributed by noncontrolling interests				0
Distributions to noncontrolling interests				0		0
Equity, end of period		5,490,000,000	5,225,000,000	5,490,000,000		5,225,000,000
San Diego Gas and Electric Company [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				53,000,000		60,000,000
Cumulative-effect adjustment from change in accounting principle							0
Comprehensive income (loss)				3,000,000		20,000,000
Common stock dividends declared				0		0
Equity contributed by noncontrolling interests				1,000,000
Distributions to noncontrolling interests				(7,000,000)		(16,000,000)
Equity, end of period		50,000,000	64,000,000	50,000,000		64,000,000
Southern California Gas Company [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning of period				3,149,000,000	[1]	2,781,000,000
Cumulative-effect adjustment from change in accounting principle							$ 15,000,000
Comprehensive income (loss)				200,000,000		277,000,000
Common stock dividends declared						(50,000,000)
Preferred stock dividends declared		0	0	(1,000,000)		(1,000,000)
Equity, end of period		$ 3,363,000,000	$ 3,007,000,000	$ 3,363,000,000		$ 3,007,000,000

[1] Derived from audited financial statements.