OTHER FINANCIAL DATA - SHAREHOLDER'S EQUITY AND NONCONTROLLING INTEREST (Details) - USD ($)		3 Months Ended			6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016		Dec. 31, 2015
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
Comprehensive income (loss)					739,000,000		346,000,000
Preferred dividends of subsidiary		$ (1,000,000)	$ (1,000,000)	[2]	(1,000,000)		(1,000,000)	[2]
Share-based compensation expense					23,000,000		24,000,000
Common stock dividends declared					(413,000,000)		(377,000,000)
Issuances of common stock					55,000,000		56,000,000
Repurchases of common stock					(14,000,000)		(54,000,000)
Equity contributed by noncontrolling interest					1,000,000		1,000,000
Distributions to noncontrolling interests					(26,000,000)		(11,000,000)
Equity, end of period		15,605,000,000	12,670,000,000		15,605,000,000		12,670,000,000
Equity, end of period		13,332,000,000			13,332,000,000
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
Comprehensive income (loss)					731,000,000		324,000,000
Preferred dividends of subsidiary					(1,000,000)		(1,000,000)
Share-based compensation expense					23,000,000		24,000,000
Common stock dividends declared					(413,000,000)		(377,000,000)
Issuances of common stock					55,000,000		56,000,000
Repurchases of common stock					(14,000,000)		(54,000,000)
Equity contributed by noncontrolling interest					0		0
Distributions to noncontrolling interests					0		0
Equity, end of period		13,332,000,000	11,888,000,000		13,332,000,000		11,888,000,000
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
Comprehensive income (loss)					8,000,000		22,000,000
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					1,000,000		1,000,000
Distributions to noncontrolling interests					(26,000,000)		(11,000,000)
Equity, end of period		2,273,000,000	782,000,000		2,273,000,000		782,000,000
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
Comprehensive income (loss)					314,000,000		223,000,000
Common stock dividends declared					(175,000,000)		(175,000,000)
Equity contributed by noncontrolling interest					1,000,000
Distributions to noncontrolling interests					(14,000,000)		(3,000,000)
Equity, end of period		5,804,000,000	5,344,000,000		5,804,000,000		5,344,000,000
Equity, end of period		5,770,000,000			5,770,000,000
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
Comprehensive income (loss)					304,000,000		236,000,000
Common stock dividends declared					(175,000,000)		(175,000,000)
Equity contributed by noncontrolling interest					0
Distributions to noncontrolling interests					0		0
Equity, end of period		5,770,000,000	5,307,000,000		5,770,000,000		5,307,000,000
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
Comprehensive income (loss)					10,000,000		(13,000,000)
Common stock dividends declared					0		0
Equity contributed by noncontrolling interest					1,000,000
Distributions to noncontrolling interests					(14,000,000)		(3,000,000)
Equity, end of period		34,000,000	37,000,000		34,000,000		37,000,000
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
Comprehensive income (loss)					263,000,000		199,000,000
Preferred stock dividends declared		(1,000,000)	(1,000,000)		(1,000,000)		(1,000,000)
Equity, end of period		$ 3,772,000,000	$ 3,362,000,000		$ 3,772,000,000		$ 3,362,000,000

[1] Derived from audited financial statements.

[2] As adjusted for the adoption of ASU 2016-09 as of January 1, 2016.