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Income Taxes (Textual) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Income Tax Disclosure [Line Items]      
Deferred tax assets, loss and credit carryforwards $ 1,515 $ 689  
Deferred tax assets, valuation allowance 1,017 0  
Earnings benefit from change in prior year tax deductions 231    
Earnings benefit from change in tax deductions, current year earnings benefit 115    
Unrecognized tax benefits that would impact the effective tax rate 622 532  
Federal statutory income tax rate (percent) 35.00% 35.00% 35.00%
IRS Examination
     
Income Tax Disclosure [Line Items]      
Tax credit carryforwards 309    
Operating loss carryforwards 1,200    
Estimated potential future federal tax payment as of the balance sheet date, including interest and penalties, based on a proposed adjustment 198    
Penalty for understatement of tax liability (as a percent) 40.00%    
Tax Credit Carryforward, expire between 2029 - 2032 | IRS Examination
     
Income Tax Disclosure [Line Items]      
Tax credit carryforwards 287    
Net Operating Loss, expire between 2015 - 2024 | IRS Examination
     
Income Tax Disclosure [Line Items]      
Operating loss carryforwards 26    
Southern California Edison
     
Income Tax Disclosure [Line Items]      
Deferred tax assets, loss and credit carryforwards 125 15  
Deferred tax assets, valuation allowance 0 0  
Unrecognized tax benefits that would impact the effective tax rate 388 282  
Southern California Edison | IRS Examination
     
Income Tax Disclosure [Line Items]      
Tax credit carryforwards 42    
Operating loss carryforwards 83    
Estimated potential future federal tax payment as of the balance sheet date, including interest and penalties, based on a proposed adjustment 96    
Southern California Edison | Tax Credit Carryforward, expire between 2030 - 2032 | IRS Examination
     
Income Tax Disclosure [Line Items]      
Tax credit carryforwards 28    
Southern California Edison | Net Operating Loss, expire between 2015 -2016 | IRS Examination
     
Income Tax Disclosure [Line Items]      
Operating loss carryforwards 12    
Edison Mission Energy
     
Income Tax Disclosure [Line Items]      
Tax basis in stock $ 542