Derivatives - Pre-tax Effects of Derivatives Designated as Cash Flow Hedging Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																																																																																3 Months Ended
	Mar. 31, 2013 Interest Expense [Member]	Mar. 31, 2012 Interest Expense [Member]	Mar. 31, 2013 Interest Expense [Member] Alabama Power [Member]	Mar. 31, 2012 Interest Expense [Member] Alabama Power [Member]	Mar. 31, 2013 Interest Expense [Member] Georgia Power [Member]	Mar. 31, 2012 Interest Expense [Member] Georgia Power [Member]	Mar. 31, 2013 Interest Expense [Member] Mississippi Power [Member]	Mar. 31, 2012 Interest Expense [Member] Mississippi Power [Member]	Mar. 31, 2013 Interest Expense [Member] Southern Power [Member]	Mar. 31, 2012 Interest Expense [Member] Southern Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member]	Dec. 31, 2012 Energy-related derivatives [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Alabama Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Alabama Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Georgia Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Georgia Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Gulf Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Gulf Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Mississippi Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Mississippi Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets current [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets current [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets current [Member] Alabama Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets current [Member] Alabama Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets current [Member] Georgia Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets current [Member] Georgia Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets current [Member] Gulf Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets current [Member] Gulf Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets current [Member] Mississippi Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets current [Member] Mississippi Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets deferred [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets deferred [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Alabama Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Alabama Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Georgia Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Georgia Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Gulf Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Gulf Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Mississippi Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory assets deferred [Member] Mississippi Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities current [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities current [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Alabama Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Alabama Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Georgia Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Georgia Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Gulf Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Gulf Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Mississippi Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities current [Member] Mississippi Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Alabama Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Alabama Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Georgia Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Georgia Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Gulf Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Gulf Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Mississippi Power [Member]	Dec. 31, 2012 Energy-related derivatives [Member] Other regulatory liabilities deferred [Member] Mississippi Power [Member]	Mar. 31, 2013 Energy-related derivatives [Member] Other deferred credits and liabilities [Member]		Dec. 31, 2012 Energy-related derivatives [Member] Other deferred credits and liabilities [Member]		Mar. 31, 2013 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Alabama Power [Member]		Dec. 31, 2012 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Alabama Power [Member]		Mar. 31, 2013 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Georgia Power [Member]		Dec. 31, 2012 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Georgia Power [Member]		Mar. 31, 2013 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Gulf Power [Member]		Dec. 31, 2012 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Gulf Power [Member]		Mar. 31, 2013 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Mississippi Power [Member]		Dec. 31, 2012 Energy-related derivatives [Member] Other deferred credits and liabilities [Member] Mississippi Power [Member]		Mar. 31, 2013 Interest rate derivatives [Member]	Mar. 31, 2012 Interest rate derivatives [Member]	Mar. 31, 2013 Interest rate derivatives [Member] Alabama Power [Member]	Mar. 31, 2012 Interest rate derivatives [Member] Alabama Power [Member]	Mar. 31, 2013 Interest rate derivatives [Member] Georgia Power [Member]	Mar. 31, 2012 Interest rate derivatives [Member] Georgia Power [Member]	Mar. 31, 2013 Interest rate derivatives [Member] Mississippi Power [Member]	Mar. 31, 2012 Interest rate derivatives [Member] Mississippi Power [Member]	Mar. 31, 2013 Interest rate derivatives [Member] Southern Power [Member]	Mar. 31, 2012 Interest rate derivatives [Member] Southern Power [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total energy-related derivative gains (losses)											$ (17)	$ (86)	$ 5	$ (13)	$ (15)	$ (34)	$ (2)	$ (23)	$ (5)	$ (16)	$ (36)	$ (74)	$ (5)	$ (14)	$ (17)	$ (30)	$ (8)	$ (17)	$ (6)	$ (13)	$ (26)	$ (35)	$ (2)	$ (4)	$ (11)	$ (15)	$ (8)	$ (10)	$ (5)	$ (6)	$ 25	$ 10	$ 7	$ 2	$ 6	$ 6	$ 9	$ 1	$ 3	$ 1	$ 20	$ 13	$ 5	$ 3	$ 0	$ 0	$ 5	$ 3	$ 3	$ 2	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 7	[1]	$ 5	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]
Pre-tax effect of derivatives designated as cash flow hedging instruments
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)																																																																																	0	6	0	7	0	0	0	(1)	0	0
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	$ (5)	$ (3)	$ (1)	$ 0	$ (1)	$ (1)	$ 0	$ 0	$ (3)	$ (2)

[1] Georgia Power includes Other regulatory liabilities, deferred in Other deferred credits and liabilities.