Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (USD $)	Dec. 31, 2012		Dec. 31, 2011
Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	$ 26,000,000		$ 14,000,000
Interest rate derivatives	10,000,000		13,000,000
Foreign Currency Derivative Assets at Fair Value			2,000,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	384,000,000		1,024,000,000
Other	24,000,000		67,000,000
Fair value assets, total	1,746,000,000		2,325,000,000
Liabilities:
Energy-related derivatives	111,000,000		245,000,000
Interest rate derivatives			33,000,000
Foreign currency derivatives			3,000,000
Fair value liabilities, total			281,000,000
Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	518,000,000	[1]	454,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	200,000,000	[1]	172,000,000	[1]
Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	134,000,000	[1]	50,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	55,000,000	[1]	82,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	234,000,000	[1]	260,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	141,000,000	[1]	151,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	20,000,000	[1]	36,000,000	[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
Foreign Currency Derivative Assets at Fair Value			0
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	384,000,000		1,024,000,000
Other	9,000,000		3,000,000
Fair value assets, total	874,000,000		1,564,000,000
Liabilities:
Energy-related derivatives	0		0
Interest rate derivatives			0
Foreign currency derivatives			0
Fair value liabilities, total			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	453,000,000	[1]	396,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	28,000,000	[1]	124,000,000	[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]	17,000,000	[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	26,000,000		14,000,000
Interest rate derivatives	10,000,000		13,000,000
Foreign Currency Derivative Assets at Fair Value			2,000,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Other	0		50,000,000
Fair value assets, total	857,000,000		747,000,000
Liabilities:
Energy-related derivatives	111,000,000		245,000,000
Interest rate derivatives			33,000,000
Foreign currency derivatives			3,000,000
Fair value liabilities, total			281,000,000
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	65,000,000	[1]	58,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	172,000,000	[1]	48,000,000	[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	134,000,000	[1]	33,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	55,000,000	[1]	82,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	234,000,000	[1]	260,000,000	[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	141,000,000	[1]	151,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	20,000,000	[1]	36,000,000	[1]
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0		0
Interest rate derivatives	0		0
Foreign Currency Derivative Assets at Fair Value			0
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Other	15,000,000		14,000,000
Fair value assets, total	15,000,000		14,000,000
Liabilities:
Energy-related derivatives	0		0
Interest rate derivatives			0
Foreign currency derivatives			0
Fair value liabilities, total			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 [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	0	[1]	0	[1]
Southern Power [Member]
Assets:
Energy-related derivatives	2,100,000		600,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	26,000,000		14,200,000
Fair value assets, total	28,100,000		14,800,000
Liabilities:
Energy-related derivatives	1,300,000		9,800,000
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 and restricted cash	26,000,000		14,200,000
Fair value assets, total	26,000,000		14,200,000
Liabilities:
Energy-related derivatives	0		0
Southern Power [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	2,100,000		600,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Fair value assets, total	2,100,000		600,000
Liabilities:
Energy-related derivatives	1,300,000		9,800,000
Southern Power [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0		0
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Fair value assets, total	0		0
Liabilities:
Energy-related derivatives	0		0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	4,358,000		198,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	15,231,000		13,949,000
Fair value assets, total	19,589,000		14,147,000
Liabilities:
Energy-related derivatives	27,112,000		40,983,000
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 and restricted cash	15,231,000		13,949,000
Fair value assets, total	15,231,000		13,949,000
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	4,358,000		198,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Fair value assets, total	4,358,000		198,000
Liabilities:
Energy-related derivatives	27,112,000		40,983,000
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 and restricted cash	0		0
Fair value assets, total	0		0
Liabilities:
Energy-related derivatives	0		0
Mississippi Power [Member]
Assets:
Energy-related derivatives	2,519,000		162,000
Foreign Currency Derivative Assets at Fair Value	0		1,526,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	125,600,000		133,900,000
Fair value assets, total	128,119,000		135,588,000
Liabilities:
Energy-related derivatives	19,446,000		51,152,000
Interest rate derivatives	0		15,208,000
Foreign currency derivatives	37,000		2,510,000
Fair value liabilities, total	19,483,000		68,870,000
Mississippi Power [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	0		0
Foreign Currency Derivative Assets at Fair Value	0		0
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	125,600,000		133,900,000
Fair value assets, total	125,600,000		133,900,000
Liabilities:
Energy-related derivatives	0		0
Interest rate 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	2,519,000		162,000
Foreign Currency Derivative Assets at Fair Value	0		1,526,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Fair value assets, total	2,519,000		1,688,000
Liabilities:
Energy-related derivatives	19,446,000		51,152,000
Interest rate derivatives	0		15,208,000
Foreign currency derivatives	37,000		2,510,000
Fair value liabilities, total	19,483,000		68,870,000
Mississippi Power [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0		0
Foreign Currency Derivative Assets at Fair Value	0		0
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Fair value assets, total	0		0
Liabilities:
Energy-related derivatives	0		0
Interest rate derivatives	0		0
Foreign currency derivatives	0		0
Fair value liabilities, total	0		0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	11,000,000		13,000,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	15,000,000		13,000,000
Fair value assets, total	724,000,000		692,000,000
Liabilities:
Energy-related derivatives	45,000,000		95,000,000
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	163,000,000	[1]	144,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	117,000,000	[1]	100,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	105,000,000	[1]	25,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	55,000,000	[1]	82,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	133,000,000	[1]	167,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	115,000,000	[1]	123,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	10,000,000	[1]	25,000,000	[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 and restricted cash	15,000,000		13,000,000
Fair value assets, total	177,000,000		256,000,000
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	162,000,000	[1]	143,000,000	[1]
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	0	[1]	100,000,000	[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	11,000,000		13,000,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash	0		0
Fair value assets, total	547,000,000		436,000,000
Liabilities:
Energy-related derivatives	45,000,000		95,000,000
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 [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	117,000,000	[1]	0	[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	105,000,000	[1]	25,000,000	[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	55,000,000	[1]	82,000,000	[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	133,000,000	[1]	167,000,000	[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	115,000,000	[1]	123,000,000	[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	10,000,000	[1]	25,000,000	[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 and restricted cash	0		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 [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]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	5,000,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash			209,000,000
Fair value assets, total	609,000,000		748,000,000
Liabilities:
Energy-related derivatives	18,000,000		48,000,000
Interest rate derivatives			18,000,000
Fair value liabilities, total			66,000,000
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	355,000,000	[2]	310,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	83,000,000	[2]	72,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	29,000,000	[2]	25,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	101,000,000	[2]	93,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	26,000,000	[2]	28,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	10,000,000	[2]	11,000,000	[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
Nuclear decommissioning trusts:
Cash equivalents and restricted cash			209,000,000
Fair value assets, total	319,000,000		503,000,000
Liabilities:
Energy-related derivatives	0		0
Interest rate derivatives			0
Fair value liabilities, total			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	291,000,000	[2]	253,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	28,000,000	[2]	24,000,000	[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]	17,000,000	[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	5,000,000
Nuclear decommissioning trusts:
Cash equivalents and restricted cash			0
Fair value assets, total	290,000,000		245,000,000
Liabilities:
Energy-related derivatives	18,000,000		48,000,000
Interest rate derivatives			18,000,000
Fair value liabilities, total			66,000,000
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	64,000,000	[2]	57,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign Equity [Member]
Nuclear decommissioning trusts:
Nuclear decommissioning trusts	55,000,000	[2]	48,000,000	[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	29,000,000	[2]	8,000,000	[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	101,000,000	[2]	93,000,000	[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	26,000,000	[2]	28,000,000	[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	10,000,000	[2]	11,000,000	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Nuclear decommissioning trusts:
Cash equivalents and restricted cash			0
Fair value assets, total	0		0
Liabilities:
Energy-related derivatives	0		0
Interest rate derivatives			0
Fair value liabilities, total			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	[2]
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign Equity [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	$ 0	[2]	$ 0	[2]

[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.