XML 40 R40.htm IDEA: XBRL DOCUMENT v2.4.0.8
Regulatory Matters - Other Regulatory Matters - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
1 Months Ended 9 Months Ended
Sep. 30, 2013
Aug. 31, 2013
Jan. 31, 2013
Sep. 30, 2013
Dec. 31, 2012
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Revenues from electric       $ 249  
Revenues from gas       32  
Revenues from steam service       6  
Potential refund to customers       1,318  
Overcharges of construction expenditures       208  
Refund amount 16     16  
Regulatory asset 9,236     9,236 9,779
Minimum [Member]
         
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Refund amount 16     16  
Maximum [Member]
         
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Overcharges of construction expenditures       208  
Storm Damage [Member]
         
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Number of customers interrupted electric distribution service       1,400,000  
Rockland Electric Company [Member] | Storm Costs [Member]
         
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Regulatory asset 28     28  
Capital expenditures       6  
CECONY [Member]
         
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Electric rate increases 418   375    
Gas rate increases 27   25    
Steam rate decreases   10 5    
Return on common equity 10.10% 8.70% 10.35%    
Common equity ratio 50.00% 48.00% 50.00%    
Electric rate decreases   146      
Gas rate decreases   95      
Steam rate increases 8        
Response and restoration costs       471  
Capital expenditures       143  
Regulatory asset 8,539     8,539 9,032
O&R [Member]
         
Schedule Of Regulatory Assets And Liabilities [Line Items]          
Response and restoration costs       92  
Capital expenditures       $ 15