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.