Financing - Narrative (Details) (USD $)	9 Months Ended					9 Months Ended			0 Months Ended	9 Months Ended							9 Months Ended			1 Months Ended				1 Months Ended		9 Months Ended			1 Months Ended		9 Months Ended							0 Months Ended		0 Months Ended	1 Months Ended
	Sep. 30, 2014		Aug. 01, 2014 Senior Notes [Member] Series 2014A [Member]	Aug. 01, 2014 Senior Notes [Member] Series 2014B [Member]	Sep. 30, 2014 Traditional Operating Companies [Member]	Sep. 30, 2014 Alabama Power [Member]		Aug. 01, 2014 Alabama Power [Member] Senior Notes [Member] Series 2014A [Member]	Feb. 20, 2014 Georgia Power [Member]	Sep. 30, 2014 Georgia Power [Member]		Sep. 30, 2013 Georgia Power [Member]	Feb. 20, 2014 Georgia Power [Member]	Jul. 31, 2014 Georgia Power [Member] FIrst Series 2009 [Member]	Feb. 20, 2014 Georgia Power [Member] Line of Credit [Member] Debt Due 2044 [Member]	Feb. 20, 2014 Georgia Power [Member] Line of Credit [Member] Debt Due 2029 [Member]	Sep. 30, 2014 Gulf Power [Member]		Sep. 30, 2013 Gulf Power [Member]	Jun. 30, 2014 Gulf Power [Member] Series 2012 [Member]	Sep. 30, 2014 Gulf Power [Member] Senior Notes [Member] Series 2014A [Member]	Apr. 01, 2014 Gulf Power [Member] Debt Issuances [Member]	Apr. 01, 2014 Gulf Power [Member] Debt Redemptions [Member]	May 31, 2014 Mississippi Power [Member]	Jan. 31, 2014 Mississippi Power [Member]	Sep. 30, 2014 Mississippi Power [Member]		Sep. 30, 2013 Mississippi Power [Member]	Aug. 31, 2014 Mississippi Power [Member] Series 2013A [Member]	May 31, 2014 Mississippi Power [Member] Series 2013A [Member]	Sep. 30, 2014 Southern Power [Member]		Sep. 30, 2014 Southern Power [Member] Debt Due April 30, 2034 [Member]	Sep. 30, 2014 Southern Power [Member] Debt Due May 31, 2034 [Member]	Sep. 30, 2014 Southern Power [Member] Debt Due April 30, 2033 [Member]	Sep. 30, 2014 Southern Power [Member] Debt Due June 15, 2032 [Member]	Feb. 20, 2014 Plant Vogtle Units 3 And 4 [Member] Georgia Power [Member]	Oct. 01, 2014 Subsequent Event [Member] Gulf Power [Member] Series K [Member]	Oct. 01, 2014 Subsequent Event [Member] Gulf Power [Member] Senior Notes [Member] Series K [Member]	Oct. 09, 2014 Subsequent Event [Member] Mississippi Power [Member]	Nov. 06, 2014 Subsequent Event [Member] Mississippi Power [Member]
Debt Instrument [Line Items]
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support	$ 1,800,000,000				$ 423,000,000					$ 98,000,000
Debt Instrument, Face Amount			400,000,000	350,000,000				400,000,000							500,000,000	500,000,000					200,000,000
Debt Instrument, Interest Rate, Stated Percentage			1.30%	2.15%				4.15%							3.86%	3.488%					4.55%																		4.90%
Line of Credit Facility, Current Borrowing Capacity													1,000,000,000
Jointly Owned Utility Plant, Proportionate Ownership Share																																					45.70%
Payments of Debt Issuance Costs									66,000,000
Long-term Pollution Control Bond														40,000,000								29,075,000.000	29,075,000.000
Revenue Bond Issuances	82,000,000	[1]				0	[1]			40,000,000	[1]						42,000,000	[1]		13,000,000						0	[1]				0	[1]
Repayments of Senior Debt										0		1,250,000,000					0		90,000,000																			75,000,000
Bank Loans Period Of Extension																								19 months	18 months
Debt Instrument, Description of Variable Rate Basis																								one-month LIBOR	one-month LIBOR
Aggregate Principal Amount Of Floating Rate Bank Loan																								220,000,000	250,000,000
Interest Bearing Refundable Deposit Related to Asset Sale																									75,000,000	75,000,000		0												50,000,000	50,000,000
Taxable Revenue Bond																													10,500,000	12,300,000
Repayments of Long-term Debt																															800,000
Promissory Note																																	$ 3,900,000	$ 5,300,000	$ 800,000	$ 100,000

[1] Includes remarketing by Gulf Power of $13 million aggregate principal amount of revenue bonds previously purchased and held by Gulf Power since December 2013 and remarketing by Georgia Power of $40 million aggregate principal amount of revenue bonds previously purchased and held by Georgia Power since 2010.