Derivatives - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2014 MMBTU
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	7,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	$ 2,000,000
Alabama Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	2,000,000
Georgia Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	4,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	2,000,000
Gulf Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	2,000,000
Mississippi Power [Member]
Derivatives (Textual) [Abstract]
Maximum potential collateral requirements arising the from credit-risk-related contingent features	2,000,000
Southern Power [Member]
Derivatives (Textual) [Abstract]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	1,000,000
Maximum potential collateral requirements arising the from credit-risk-related contingent features	$ 2,000,000
Agreement Through Two Thousand Fifteen [Member] | Gulf Power [Member]
Derivative [Line Items]
Wholesale Capacity Percentage	100.00%
Agreement Through Two Thousand Nineteen [Member] | Gulf Power [Member]
Derivative [Line Items]
Wholesale Capacity Percentage	57.00%