Derivatives - Schedule of Derivatives and Gains (Losses) (Details) BTU in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) BTU
Southern Company [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	250
Longest Hedge Date	2020
Longest Non-Hedge Date	2016
Alabama Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	60
Longest Hedge Date	2019
Georgia Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	82
Longest Hedge Date	2019
Gulf Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	66
Longest Hedge Date	2020
Mississippi Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	29
Longest Hedge Date	2019
Southern Power [Member] | Maturity Date October 2016 [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Derivative term	15 years
Southern Power [Member] | Maturity Date November 2016 [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Derivative term	12 years
Southern Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	13
Longest Hedge Date	2017
Longest Non-Hedge Date	2016
Interest Rate Contract [Member]
Interest rate derivatives
Notional Amount	$ 1,968
Fair Value Gain (Loss) at June 30, 2016	20
Interest Rate Contract [Member] | Southern Company [Member] | Maturity Date June 2020 Number One [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 8
Weighted Average Interest Rate Paid	1.73%
Fair Value Gain (Loss) at June 30, 2016	$ 0
Interest Rate Contract [Member] | Southern Company [Member] | Maturity Date June 2020 Number Two [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 3
Weighted Average Interest Rate Paid	1.73%
Fair Value Gain (Loss) at June 30, 2016	$ 0
Interest Rate Contract [Member] | Southern Company [Member] | Maturity Date August 2017 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 250
Interest Rate Received	1.30%
Fair Value Gain (Loss) at June 30, 2016	$ 2
Interest Rate Contract [Member] | Southern Company [Member] | Maturity Date August 2017 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	0.17%
Interest Rate Contract [Member] | Southern Company [Member] | Maturity Date June 2020 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 300
Interest Rate Received	2.75%
Fair Value Gain (Loss) at June 30, 2016	$ 11
Interest Rate Contract [Member] | Southern Company [Member] | Maturity Date June 2020 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	0.92%
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date August 2016 [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 200
Weighted Average Interest Rate Paid	1.01%
Fair Value Gain (Loss) at June 30, 2016	$ 0
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date August 2016 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Interest Rate Received	0.40%
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date June 2018 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 250
Interest Rate Received	5.40%
Fair Value Gain (Loss) at June 30, 2016	$ 3
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date June 2018 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	4.02%
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date December 2019 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 200
Interest Rate Received	4.25%
Fair Value Gain (Loss) at June 30, 2016	$ 6
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date December 2019 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	2.46%
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date December 2018 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 500
Interest Rate Received	1.95%
Fair Value Gain (Loss) at June 30, 2016	$ 5
Interest Rate Contract [Member] | Georgia Power [Member] | Maturity Date December 2018 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	0.76%
Interest Rate Contract [Member] | Gulf Power [Member] | Maturity Date December 2026 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Interest rate derivatives
Notional Amount	$ 80
Weighted Average Interest Rate Paid	2.32%
Fair Value Gain (Loss) at June 30, 2016	$ (7)
Interest Rate Contract [Member] | Southern Power [Member] | Maturity Date October 2016 Number One [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Notional Amount	$ 65
Weighted Average Interest Rate Paid	2.50%
Fair Value Gain (Loss) at June 30, 2016	$ 0
Interest Rate Contract [Member] | Southern Power [Member] | Maturity Date October 2016 [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Notional Amount	$ 47
Weighted Average Interest Rate Paid	2.21%
Fair Value Gain (Loss) at June 30, 2016	$ 0
Interest Rate Contract [Member] | Southern Power [Member] | Maturity Date November 2016 [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Notional Amount	$ 65
Weighted Average Interest Rate Paid	2.21%
Fair Value Gain (Loss) at June 30, 2016	$ 0
Foreign Exchange Contract [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Fair Value Gain (Loss) at June 30, 2016	(38)
Foreign Exchange Contract [Member] | Southern Power [Member] | Maturity Date June 2022 [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Fair Value Gain (Loss) at June 30, 2016	(17)
Foreign Exchange Contract [Member] | Southern Power [Member] | Maturity Date June 2026 [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Fair Value Gain (Loss) at June 30, 2016	$ (21)