Financing - Schedule of Long-Term Debt Financing Activities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Debt Instrument [Line Items]
Senior Note Issuances	$ 550	[1]
Senior Note Redemptions	250	[1]
Debt Redemptions [Member]
Debt Instrument [Line Items]
Other Long-Term Debt	83	[1],[2]
Alabama Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	550	[1]
Senior Note Redemptions	250	[1]
Alabama Power [Member] | Debt Redemptions [Member]
Debt Instrument [Line Items]
Other Long-Term Debt	0	[1],[2]
Georgia Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	0	[1]
Senior Note Redemptions	0	[1]
Georgia Power [Member] | Debt Redemptions [Member]
Debt Instrument [Line Items]
Other Long-Term Debt	3	[1],[2]
Mississippi Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	0	[1]
Senior Note Redemptions	0	[1]
Mississippi Power [Member] | Debt Redemptions [Member]
Debt Instrument [Line Items]
Other Long-Term Debt	76	[1],[2]
Other Subsidiaries [Member]
Debt Instrument [Line Items]
Senior Note Issuances	0	[1]
Senior Note Redemptions	0	[1]
Other Subsidiaries [Member] | Debt Redemptions [Member]
Debt Instrument [Line Items]
Other Long-Term Debt	$ 4	[1],[2]

[1] Southern Company, Gulf Power, and Southern Power did not issue or redeem any long-term debt during the first three months of 2015.

[2] Includes reductions in capital lease obligations resulting from cash payments under capital leases.