Fair Value Measurements (Details) (USD $) In Millions	Sep. 30, 2011
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents and restricted cash	$ 445
Fair value assets, total	946
Liabilities:
Energy-related derivatives	29
Interest rate derivatives	12
Fair value liabilities, total	41
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents and restricted cash	445
Fair value assets, total	712
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Fair value liabilities, total	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	228
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	23
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	16
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Cash equivalents and restricted cash	0
Fair value assets, total	234
Liabilities:
Energy-related derivatives	29
Interest rate derivatives	12
Fair value liabilities, total	41
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	53
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	23
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	9
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	112
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	29
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	8
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Cash equivalents and restricted cash	0
Fair value assets, total	0
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Fair value liabilities, total	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	281
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	46
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	25
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	112
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	29
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	8
Georgia Power [Member]
Assets:
Nuclear decommissioning trusts	53
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	2
Cash equivalents and restricted cash	45
Fair value assets, total	704
Liabilities:
Energy-related derivatives	68
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Energy-related derivatives	0
Cash equivalents and restricted cash	45
Fair value assets, total	265
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	125
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	95
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Energy-related derivatives	2
Cash equivalents and restricted cash	0
Fair value assets, total	439
Liabilities:
Energy-related derivatives	68
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	1
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	68
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	57
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	153
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	96
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	62
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Energy-related derivatives	0
Cash equivalents and restricted cash	0
Fair value assets, total	0
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	126
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Equity [Member]
Assets:
Nuclear decommissioning trusts	95
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	68
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	57
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	153
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	96
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Assets:
Nuclear decommissioning trusts	62
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents and restricted cash	14
Liabilities:
Energy-related derivatives	17
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents and restricted cash	14
Liabilities:
Energy-related derivatives	0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Cash equivalents and restricted cash	0
Liabilities:
Energy-related derivatives	17
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Cash equivalents and restricted cash	0
Liabilities:
Energy-related derivatives	0
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Foreign currency derivatives	3
Cash equivalents and restricted cash	85
Fair value assets, total	88
Liabilities:
Energy-related derivatives	35
Interest rate derivatives	15
Foreign currency derivatives	2
Fair value liabilities, total	52
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Foreign currency derivatives	0
Cash equivalents and restricted cash	85
Fair value assets, total	85
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Fair value liabilities, total	0
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Foreign currency derivatives	3
Cash equivalents and restricted cash	0
Fair value assets, total	3
Liabilities:
Energy-related derivatives	35
Interest rate derivatives	15
Foreign currency derivatives	2
Fair value liabilities, total	52
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Foreign currency derivatives	0
Cash equivalents and restricted cash	0
Fair value assets, total	0
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Fair value liabilities, total	0
Southern Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	1
Cash equivalents and restricted cash	196
Fair value assets, total	197
Liabilities:
Energy-related derivatives	5
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Energy-related derivatives	0
Cash equivalents and restricted cash	196
Fair value assets, total	196
Liabilities:
Energy-related derivatives	0
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Energy-related derivatives	1
Cash equivalents and restricted cash	0
Fair value assets, total	1
Liabilities:
Energy-related derivatives	5
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Energy-related derivatives	0
Cash equivalents and restricted cash	0
Fair value assets, total	0
Liabilities:
Energy-related derivatives	0
Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	3
Interest rate derivatives	16
Foreign currency derivatives	3
Nuclear decommissioning trusts	1,158
Cash equivalents and restricted cash	1,286
Other	70
Fair value assets, total	2,536
Liabilities:
Energy-related derivatives	154
Interest rate derivatives	27
Foreign currency derivatives	2
Fair value liabilities, total	183
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Nuclear decommissioning trusts	487
Cash equivalents and restricted cash	1,286
Other	4
Fair value assets, total	1,777
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Fair value liabilities, total	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Energy-related derivatives	3
Interest rate derivatives	16
Foreign currency derivatives	3
Nuclear decommissioning trusts	671
Cash equivalents and restricted cash	0
Other	53
Fair value assets, total	746
Liabilities:
Energy-related derivatives	154
Interest rate derivatives	27
Foreign currency derivatives	2
Fair value liabilities, total	183
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Nuclear decommissioning trusts	0
Cash equivalents and restricted cash	0
Other	13
Fair value assets, total	13
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Fair value liabilities, total	$ 0