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Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (USD $)
Dec. 31, 2013
Dec. 31, 2012
Fair Value, Measurements, Recurring [Member]
    
Assets:    
Energy-related derivatives $ 24,000,000 $ 26,000,000
Interest rate derivatives 3,000,000 10,000,000
Nuclear decommissioning trusts:    
Cash equivalents 491,000,000 384,000,000
Other investments 13,000,000 24,000,000
Fair value assets, total 1,994,000,000 1,746,000,000
Liabilities:    
Energy-related derivatives 56,000,000 111,000,000
Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 664,000,000 [1] 518,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 231,000,000 [1] 200,000,000 [1]
Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 103,000,000 [1] 134,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 64,000,000 [1] 55,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 229,000,000 [1] 234,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 132,000,000 [1] 141,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 40,000,000 [1] 20,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
    
Assets:    
Energy-related derivatives 0 0
Interest rate derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 491,000,000 384,000,000
Other investments 9,000,000 9,000,000
Fair value assets, total 1,124,000,000 874,000,000
Liabilities:    
Energy-related derivatives 0 0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 589,000,000 [1] 453,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 35,000,000 [1] 28,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
    
Assets:    
Energy-related derivatives 24,000,000 26,000,000
Interest rate derivatives 3,000,000 10,000,000
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Other investments 0 0
Fair value assets, total 863,000,000 857,000,000
Liabilities:    
Energy-related derivatives 56,000,000 111,000,000
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 75,000,000 [1] 65,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 196,000,000 [1] 172,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 103,000,000 [1] 134,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 64,000,000 [1] 55,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 229,000,000 [1] 234,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 132,000,000 [1] 141,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 37,000,000 [1] 20,000,000 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
    
Assets:    
Energy-related derivatives 0 0
Interest rate derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Other investments 4,000,000 15,000,000
Fair value assets, total 7,000,000 15,000,000
Liabilities:    
Energy-related derivatives 0 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 3,000,000 [1] 0 [1]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member]
    
Assets:    
Energy-related derivatives 7,000,000 5,000,000
Nuclear decommissioning trusts:    
Cash equivalents 236,000,000 [2]  
Fair value assets, total 956,000,000 609,000,000
Liabilities:    
Energy-related derivatives 8,000,000 18,000,000
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 466,000,000 [2] 355,000,000 [3]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 100,000,000 [2] 83,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 24,000,000 [2] 29,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 89,000,000 [2] 101,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 18,000,000 [2] 26,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 16,000,000 [2] 10,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 236,000,000 [2]  
Fair value assets, total 663,000,000 319,000,000
Liabilities:    
Energy-related derivatives 0 0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 392,000,000 [2] 291,000,000 [3]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 35,000,000 [2] 28,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
    
Assets:    
Energy-related derivatives 7,000,000 5,000,000
Nuclear decommissioning trusts:    
Cash equivalents 0 [2]  
Fair value assets, total 290,000,000 290,000,000
Liabilities:    
Energy-related derivatives 8,000,000 18,000,000
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 74,000,000 [2] 64,000,000 [3]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 65,000,000 [2] 55,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 24,000,000 [2] 29,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 89,000,000 [2] 101,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 18,000,000 [2] 26,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 13,000,000 [2] 10,000,000 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 0 [2]  
Fair value assets, total 3,000,000 0
Liabilities:    
Energy-related derivatives 0 0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [3]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [2] 0 [2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 3,000,000 [2] 0 [2]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member]
    
Assets:    
Energy-related derivatives 5,000,000 11,000,000
Nuclear decommissioning trusts:    
Cash equivalents   15,000,000
Fair value assets, total 755,000,000 724,000,000
Liabilities:    
Energy-related derivatives 21,000,000 45,000,000
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 198,000,000 [1] 163,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 131,000,000 [1] 117,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 79,000,000 [1] 105,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 64,000,000 [1] 55,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 140,000,000 [1] 133,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 114,000,000 [1] 115,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 24,000,000 [1] 10,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents   15,000,000
Fair value assets, total 197,000,000 177,000,000
Liabilities:    
Energy-related derivatives 0 0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 197,000,000 [1] 162,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
    
Assets:    
Energy-related derivatives 5,000,000 11,000,000
Nuclear decommissioning trusts:    
Cash equivalents   0
Fair value assets, total 558,000,000 547,000,000
Liabilities:    
Energy-related derivatives 21,000,000 45,000,000
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 1,000,000 [1] 1,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 131,000,000 [1] 117,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 79,000,000 [1] 105,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 64,000,000 [1] 55,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 140,000,000 [1] 133,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 114,000,000 [1] 115,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 24,000,000 [1] 10,000,000 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents   0
Fair value assets, total 0 0
Liabilities:    
Energy-related derivatives 0 0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity fund [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
    
Nuclear decommissioning trusts:    
Nuclear decommissioning trusts 0 [1] 0 [1]
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member]
    
Assets:    
Energy-related derivatives 6,962,000 4,358,000
Nuclear decommissioning trusts:    
Cash equivalents 15,929,000 15,231,000
Fair value assets, total 22,891,000 19,589,000
Liabilities:    
Energy-related derivatives 17,043,000 27,112,000
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 15,929,000 15,231,000
Fair value assets, total 15,929,000 15,231,000
Liabilities:    
Energy-related derivatives 0 0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
    
Assets:    
Energy-related derivatives 6,962,000 4,358,000
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Fair value assets, total 6,962,000 4,358,000
Liabilities:    
Energy-related derivatives 17,043,000 27,112,000
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Fair value assets, total 0 0
Liabilities:    
Energy-related derivatives 0 0
Mississippi Power [Member]
    
Assets:    
Energy-related derivatives 4,803,000 2,519,000
Nuclear decommissioning trusts:    
Cash equivalents 125,000,000 125,600,000
Fair value assets, total 129,803,000 128,119,000
Liabilities:    
Energy-related derivatives 10,281,000 19,446,000
Foreign currency derivatives 1,000 37,000
Fair value liabilities, total 10,282,000 19,483,000
Mississippi Power [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 125,000,000 125,600,000
Fair value assets, total 125,000,000 125,600,000
Liabilities:    
Energy-related derivatives 0 0
Foreign currency derivatives 0 0
Fair value liabilities, total 0 0
Mississippi Power [Member] | Significant Other Observable Inputs (Level 2) [Member]
    
Assets:    
Energy-related derivatives 4,803,000 2,519,000
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Fair value assets, total 4,803,000 2,519,000
Liabilities:    
Energy-related derivatives 10,281,000 19,446,000
Foreign currency derivatives 1,000 37,000
Fair value liabilities, total 10,282,000 19,483,000
Mississippi Power [Member] | Significant Unobservable Inputs (Level 3) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Fair value assets, total 0 0
Liabilities:    
Energy-related derivatives 0 0
Foreign currency derivatives 0 0
Fair value liabilities, total 0 0
Southern Power [Member]
    
Assets:    
Energy-related derivatives 600,000 2,100,000
Nuclear decommissioning trusts:    
Cash equivalents 68,000,000 26,000,000
Fair value assets, total 68,600,000 28,100,000
Liabilities:    
Energy-related derivatives 600,000 1,300,000
Southern Power [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 68,000,000 26,000,000
Fair value assets, total 68,000,000 26,000,000
Liabilities:    
Energy-related derivatives 0 0
Southern Power [Member] | Significant Other Observable Inputs (Level 2) [Member]
    
Assets:    
Energy-related derivatives 600,000 2,100,000
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Fair value assets, total 600,000 2,100,000
Liabilities:    
Energy-related derivatives 600,000 1,300,000
Southern Power [Member] | Significant Unobservable Inputs (Level 3) [Member]
    
Assets:    
Energy-related derivatives 0 0
Nuclear decommissioning trusts:    
Cash equivalents 0 0
Fair value assets, total 0 0
Liabilities:    
Energy-related derivatives $ 0 $ 0
[1] Includes the investment securities pledged to creditors and collateral received, and excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases and the lending pool. See Note 1 under "Nuclear Decommissioning" for additional information.
[2] Excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases. See Note 1 under "Nuclear Decommissioning" for additional information.
[3] Excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases.