OTHER FINANCIAL DATA - COMPREHENSIVE INCOME AND EQUITY (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				$ 12,100	[1]	$ 11,850
Comprehensive income (loss)				773		788
Share-based compensation expense				39		35
Common stock dividends declared				(520)		(486)
Preferred dividends of subsidiary		$ 0	$ 0	(1)		(1)
Issuance of common stock				82		71
Tax benefit related to share-based compensation				56		22
Repurchases of common stock				(74)		(38)
Noncontrolling Interest Increase				1		1
Distributions to noncontrolling interests				(60)		(85)
Equity, end of period		12,396	12,157	12,396		12,157
Ownership Interests Held By Others [Line Items]
Amount of ownership interests held by others		751		751			$ 754
San Diego Gas and Electric Company [Member]
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				4,992	[1]	4,719
Comprehensive income (loss)				463		404
Common stock dividends declared				(150)
Distributions to noncontrolling interests				(16)		(37)
Equity, end of period		5,289	5,086	5,289		5,086
Southern California Gas Company [Member]
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				2,781	[1]	2,549
Comprehensive income (loss)				277		259
Common stock dividends declared				(50)
Preferred dividend requirements		0	0	(1)		(1)
Equity, end of period		3,007	2,807	3,007		2,807
Total Shareholders' Equity
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				11,326		11,008
Comprehensive income (loss)				717		722
Share-based compensation expense				39		35
Common stock dividends declared				(520)		(486)
Preferred dividends of subsidiary				(1)		(1)
Issuance of common stock				82		71
Tax benefit related to share-based compensation				56		22
Repurchases of common stock				(74)		(38)
Noncontrolling Interest Increase				0		0
Distributions to noncontrolling interests				0		0
Equity, end of period		11,625	11,333	11,625		11,333
Total Shareholders' Equity | San Diego Gas and Electric Company [Member]
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				4,932		4,628
Comprehensive income (loss)				443		381
Common stock dividends declared				(150)
Distributions to noncontrolling interests				0		0
Equity, end of period		5,225	5,009	5,225		5,009
Noncontrolling Interests [Member]
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				774		842
Comprehensive income (loss)				56		66
Share-based compensation expense				0		0
Common stock dividends declared				0		0
Preferred dividends of subsidiary				0		0
Issuance of common stock				0		0
Tax benefit related to share-based compensation				0		0
Repurchases of common stock				0		0
Noncontrolling Interest Increase				1		1
Distributions to noncontrolling interests				(60)		(85)
Equity, end of period		771	824	771		824
Noncontrolling Interests [Member] | San Diego Gas and Electric Company [Member]
Comprehensive Income Disclosure [Line Items]
Equity, beginning of period				60		91
Comprehensive income (loss)				20		23
Common stock dividends declared				0
Distributions to noncontrolling interests				(16)		(37)
Equity, end of period		$ 64	$ 77	$ 64		$ 77
Ownership Interests Held By Others, Bay Gas Storage Company [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		9.10%		9.10%			9.10%
Amount of ownership interests held by others		$ 25		$ 25			$ 23
Ownership Interests Held By Others, Southern Gas Transmission [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		49.00%		49.00%			49.00%
Amount of ownership interests held by others		$ 1		$ 1			$ 1
Ownership Interests Held By Others, Liberty Gas Storage [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		23.70%		23.70%			25.00%
Amount of ownership interests held by others		$ 12		$ 12			$ 14
Ownership Interests Held By Others, Tecsur [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		9.80%		9.80%			9.80%
Amount of ownership interests held by others		$ 3		$ 3			$ 4
Ownership Interests Held By Others, Luz Del Sur [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		16.40%		16.40%			16.40%
Amount of ownership interests held by others		$ 171		$ 171			$ 177
Ownership Interests Held By Others, Chilquinta Energia [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others, minimum	[2]	23.50%		23.50%			23.60%
Percent of ownership held by others, maximum	[2]	43.40%		43.40%			43.40%
Amount of ownership interests held by others	[2]	$ 20		$ 20			$ 23
Otay Mesa VIE [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		100.00%		100.00%			100.00%
Amount of ownership interests held by others		$ 64		$ 64			$ 60
Ownership Interests Held By Others IEnova [Member]
Ownership Interests Held By Others [Line Items]
Percent of ownership held by others		18.90%		18.90%			18.90%
Amount of ownership interests held by others		$ 455		$ 455			$ 452

[1] Derived from audited financial statements.

[2] Chilquinta Energía has four subsidiaries with noncontrolling interests held by others. Percentage range reflects the highest and lowest ownership percentages amongst these subsidiaries.