Derivatives - Schedule of Derivatives and Gains (Losses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Notional amount of interest rate derivatives
Notional Amount	$ 350
Interest Rate Paid, basis spread on LIBOR	1.96%	[1]
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2014	(12)
Total Deferred Gains (Losses) Amortized Through	2037
Alabama Power [Member]
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2014	(3)
Total Deferred Gains (Losses) Amortized Through	2035
Georgia Power [Member]
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2014	(3)
Total Deferred Gains (Losses) Amortized Through	2037
Gulf Power [Member]
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2014	(1)
Total Deferred Gains (Losses) Amortized Through	2020
Mississippi Power [Member]
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2014	(1)
Total Deferred Gains (Losses) Amortized Through	2022
Southern Power [Member]
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2014	(4)
Total Deferred Gains (Losses) Amortized Through	2016
Fair Value Hedging [Member]
Notional amount of interest rate derivatives
Interest Rate Received	4.15%
Interest Rate Paid	3-month LIBOR  + 1.96%	[1]
Hedge Maturity Date	May 01, 2014
Fair Value Gain (Loss) March 31, 2013	$ 10
Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu	259,000,000
Longest Hedge Date	2017
Longest Non-Hedge Date	2017
Gas [Member] | Alabama Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	58,000,000
Longest Hedge Date	2017
Gas [Member] | Georgia Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	90,000,000
Longest Hedge Date	2017
Gas [Member] | Gulf Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	70,000,000
Longest Hedge Date	2017
Gas [Member] | Mississippi Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	36,000,000
Longest Hedge Date	2017
Gas [Member] | Southern Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	5,000,000
Longest Non-Hedge Date	2017

[1] Weighted average