Derivatives - Schedule of Derivatives and Gains (Losses) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Notional amount of interest rate derivatives
Notional Amount	$ 350
Fair Value Gain (Loss) September 30, 2014	(2)
Southern Company [Member]
Notional amount of interest rate derivatives
Notional Amount	250
Interest Rate Received	1.30%
Cash Flow Hedging [Member] | Alabama Power [Member]
Notional amount of interest rate derivatives
Notional Amount	100
Interest Rate Received, Description	3-month LIBOR
Weighted Average Interest Rate Paid	3.07%
Hedge Maturity Date	Oct. 01, 2025
Fair Value Gain (Loss) September 30, 2014	(1)
Fair Value Hedging [Member] | Southern Company [Member]
Notional amount of interest rate derivatives
Weighted Average Interest Rate Paid	0.17%
Weighted Average Interest Rate Paid, Description	3-month LIBOR + 0.17%
Hedge Maturity Date	Aug. 01, 2017
Fair Value Gain (Loss) September 30, 2014	$ (1)
Gas [Member] | Southern Company [Member]
Energy-related derivative contracts
Net Purchased mmBtu	232,000,000
Longest Hedge Date	2018
Longest Non-Hedge Date	2017
Gas [Member] | Alabama Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	57,000,000
Longest Hedge Date	2017
Gas [Member] | Georgia Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	47,000,000
Longest Hedge Date	2017
Gas [Member] | Gulf Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	77,000,000
Longest Hedge Date	2018
Gas [Member] | Mississippi Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	49,000,000
Longest Hedge Date	2017
Gas [Member] | Southern Power [Member]
Energy-related derivative contracts
Net Purchased mmBtu	2,000,000
Longest Non-Hedge Date	2017