Financing - Short-term Borrowings (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Short-term Debt [Line Items]
Expires, 2017	$ 30,000,000
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	803,000,000	[1]	1,482,000,000	[1]
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.30%	[1]	0.40%	[1]
Commercial paper [Member]
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	803,000,000	[1]	1,082,000,000	[1]
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.30%	[1]	0.20%	[1]
Short-term bank debt [Member]
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	0	[1]	400,000,000	[1]
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.00%	[1]	0.90%	[1]
Parent Company [Member]
Short-term Debt [Line Items]
Expires, 2017	0
Georgia Power [Member]
Short-term Debt [Line Items]
Expires, 2017	0
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding			1,047,000,000
Short-term Debt at the End of the Period, Weighted Average Interest Rate			0.50%
Georgia Power [Member] | Commercial paper [Member]
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	156,000,000		647,000,000
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.30%		0.20%
Georgia Power [Member] | Short-term bank debt [Member]
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding			400,000,000
Short-term Debt at the End of the Period, Weighted Average Interest Rate			0.90%
Alabama Power [Member]
Short-term Debt [Line Items]
Expires, 2017	0
Gulf Power [Member]
Short-term Debt [Line Items]
Expires, 2017	30,000,000	[2]
Gulf Power [Member] | Commercial paper [Member]
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	110,000,000	[3]	136,000,000	[3]
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.30%	[3]	0.20%	[3]
Mississippi Power [Member]
Short-term Debt [Line Items]
Expires, 2017	0
Short-term borrowings
Taxable Revenue Bonds			11,300,000
Southern Power [Member]
Short-term Debt [Line Items]
Expires, 2017	0
Southern Power [Member] | Commercial paper [Member]
Short-term borrowings
Short-term Debt at the End of the Period, Amount Outstanding	195,000,000
Short-term Debt at the End of the Period, Weighted Average Interest Rate	0.40%
Other Subsidiaries [Member]
Short-term Debt [Line Items]
Expires, 2017	$ 0

[1] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjQ1MzFhOWM1ZmVjMjQ1Zjk4ODFkOGZjMmQyYjdiOWRhfFRleHRTZWxlY3Rpb246OERGRTI3MTUxN0I0NzI4MTdBQTIwQkE4RkEzRjI3MjgM}

[2] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjQ1MzFhOWM1ZmVjMjQ1Zjk4ODFkOGZjMmQyYjdiOWRhfFRleHRTZWxlY3Rpb246Mjc3MUE3QkUxQkE0QjU1ODM2REUwQkE4RkE0RjNEOEIM}

[3] Commercial Paper at theEnd of the Period Amount Outstanding WeightedAverageInterestRate (in millions) December 31, 2014$110 0.3%December 31, 2013$136 0.2%