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Common Stock (Details Textual) (USD $)
12 Months Ended
Dec. 31, 2011
M
Y
Employee
Dec. 31, 2010
Dec. 31, 2009
Additional Common Stock (Textual) [Abstract]      
Risk-free rate based on the U.S Treasury yield curve 2.30% 2.40% 1.90%
Total compensation cost for stock option award recognized in income $ 22,000,000 $ 22,000,000 $ 23,000,000
Related tax benefit recognized in income 8,000,000 9,000,000 9,000,000
Total unrecognized compensation cost related to performance share award units 7,000,000    
Recognized period for unrecognized compensation cost 11    
Common Stock (Textual) [Abstract]      
Stock Issued During Period, Shares, Southern Investment Plan and employee and director stock plans 21,900,000 19,600,000  
Stock Issued During Period, Value, Southern Investment Plan and employee and director stock plans 723,000,000 629,000,000  
Common stock issued through at-the-market issuances pursuant to sales agency agreements related to Southern Company's continuous equity offering program   4,100,000  
Cash proceeds, net of fees and commissions   143,000,000  
Fees and commissions on cash proceeds   1,000,000  
Share-based compensation arrangement by Share-based payment award, number of shares reserved for issuance, pursuant to Stock-based compensation plan 107,000,000    
Shares remaining available for awards under the stock option and performance share plans 47,000,000    
Number of employee participating in stock option plan 6,955    
Share Based Compensation Arrangement by Share Based Payment Award Award Expiration Period 10 years    
Weighted average remaining contractual term for, option outstanding 6    
Weighted average remaining contractual term for, option exercisable 5    
Aggregate intrinsic value for, option outstanding 508,000,000    
Aggregate intrinsic value for, option exercisable 338,000,000    
Total unrecognized compensation cost related to stock option award 7,000,000    
Total unrecognized compensation cost related to stock option award, weighted average period 11    
Total compensation cost for stock option award recognized in income 22,000,000 22,000,000 23,000,000
Total compensation cost for stock option award recognized in income, tax benefit 8,000,000 9,000,000 9,000,000
Total intrinsic value of option exercised 155,000,000 57,000,000 9,000,000
Actual tax benefit for the tax deduction from stock option exercised 60,000,000 22,000,000 4,000,000
Cash received from issuance related to option exercise 528,000,000 198,000,000 19,000,000
Range of transfer performance shares to common stock based on actual Total Shareholder Return 0% to 200% of the original target performance share amount    
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return 0.00%    
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return 200.00%    
Stock option outstanding not included in earning per share 400,000 13,100,000  
Assumed average stock price $ 42.67 $ 38.01  
Increase in effect of options   800,000  
Undistributed retained earnings of the subsidiaries 6,000,000,000    
Performance Share Plan [Member]
     
Additional Common Stock (Textual) [Abstract]      
Vesting period of performance share units issued under Performance Share Plan End of a three-year    
Expected volatility 19.20% 20.70%  
Risk-free rate based on the U.S Treasury yield curve 1.40% 1.40%  
Dividend yield $ 1.82 $ 1.75  
Weighted-average grant date fair value, Performance share units $ 35.97 $ 30.13  
Performance share units, unvested 1,719,598 908,341  
Performance share units, granted 894,858    
Performance unit shares, forfeited 83,601    
Total compensation cost for stock option award recognized in income 18,000,000 9,000,000  
Related tax benefit recognized in income 7,000,000 4,000,000  
Total unrecognized compensation cost related to performance share award units 29,000,000    
Recognized period for unrecognized compensation cost 11    
Common Stock (Textual) [Abstract]      
Total unrecognized compensation cost related to stock option award 29,000,000    
Total unrecognized compensation cost related to stock option award, weighted average period 11    
Total compensation cost for stock option award recognized in income 18,000,000 9,000,000  
Total compensation cost for stock option award recognized in income, tax benefit $ 7,000,000 $ 4,000,000