Commitments (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2010	Dec. 31, 2012 Railcar		Dec. 31, 2011	Dec. 31, 2010
Recorded Unconditional Purchase Obligation [Line Items]
Fuel		$ 5,057,000,000		$ 6,262,000,000	$ 6,699,000,000
Expense Under Purchase Power Agreements Accounted For As Operating Leases		171,000,000		199,000,000	180,000,000
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		113,000,000
Leasing commitment, 2014		95,000,000
Leasing commitment, 2015		53,000,000
Leasing commitment, 2016		45,000,000
Leasing commitment, 2017		32,000,000
Leasing commitment, 2018 and thereafter		84,000,000
Operating leases, future minimum lease payments due		422,000,000
Operating Leases, Rent Expense		155,000,000		176,000,000	188,000,000
Southern Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel		426,257,000		454,790,000	391,535,000
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		1,300,000
Leasing commitment, 2014		1,600,000
Leasing commitment, 2015		1,400,000
Leasing commitment, 2016		1,300,000
Leasing commitment, 2017		1,300,000
Leasing commitment, 2018 and thereafter		40,300,000
Operating Leases, Rent Expense		800,000		600,000	500,000
Mississippi Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel		411,226,000		490,415,000	501,830,000
Estimated minimum lease payments for noncancelable operating leases
Management fee		38,100,000
Term of Management Fee Contract		40 years
Operating Leases, Rent Expense		11,100,000		32,600,000	38,600,000
Number of Railcars Used Under Operating Lease		229
Company's share of the leases		50.00%
Fuel cost recovery clause	3,500,000	3,600,000		2,600,000
Gulf Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel		544,936,000		662,283,000	742,322,000
Expense Under Purchase Power Agreements Accounted For As Operating Leases		24,600,000		25,100,000	25,100,000
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		18,900,000
Leasing commitment, 2014		17,500,000
Leasing commitment, 2015		1,200,000
Leasing commitment, 2016		1,000,000
Leasing commitment, 2017		1,100,000
Leasing commitment, 2018 and thereafter		0
Operating leases, future minimum lease payments due		39,700,000
Operating Leases, Rent Expense		20,100,000		21,900,000	23,100,000
Georgia Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel		2,051,000,000		2,789,000,000	3,102,000,000
Total estimated minimum long-term obligations
Purchase obligation, 2012		186,000,000
2013		184,000,000
2014		256,000,000
2015		273,000,000
2016		246,000,000
2017 and thereafter		2,818,000,000
Total		3,963,000,000
Capital Leases, Future Minimum Payments, Executory Costs		55,000,000	[1]
Capital Leases, Future Minimum Payments, Net Minimum Payments		313,000,000
Capital Leases, Future Minimum Payments, Interest Included in Payments		85,000,000	[2]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		30,000,000
Leasing commitment, 2014		24,000,000
Leasing commitment, 2015		17,000,000
Leasing commitment, 2016		10,000,000
Leasing commitment, 2017		6,000,000
Leasing commitment, 2018 and thereafter		3,000,000
Operating leases, future minimum lease payments due		90,000,000
Operating Leases, Rent Expense		34,000,000		33,000,000	35,000,000
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments		228,000,000	[3]
Alabama Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel		1,503,000,000		1,679,000,000	1,851,000,000
Expense Under Purchase Power Agreements Accounted For As Operating Leases		33,000,000		33,000,000	30,000,000
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		20,000,000
Leasing commitment, 2014		12,000,000
Leasing commitment, 2015		8,000,000
Leasing commitment, 2016		9,000,000
Leasing commitment, 2017		4,000,000
Leasing commitment, 2018 and thereafter		9,000,000
Operating leases, future minimum lease payments due		62,000,000
Operating Leases, Rent Expense		24,000,000		23,000,000	25,000,000
Plant Watson [Member] | Mississippi Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Company's share of the leases		100.00%
Plant Daniel [Member] | Mississippi Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Company's share of the leases		50.00%
Barges and Rail Cars [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		71,000,000
Leasing commitment, 2014		57,000,000
Leasing commitment, 2015		24,000,000
Leasing commitment, 2016		19,000,000
Leasing commitment, 2017		11,000,000
Leasing commitment, 2018 and thereafter		11,000,000
Operating leases, future minimum lease payments due		193,000,000
Barges and Rail Cars [Member] | Mississippi Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Average Operating Leases Future Minimum Payments Due Current		1,600,000
Barges and Rail Cars [Member] | Gulf Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		18,600,000
Leasing commitment, 2014		17,200,000
Leasing commitment, 2015		1,100,000
Leasing commitment, 2016		900,000
Leasing commitment, 2017		1,000,000
Leasing commitment, 2018 and thereafter		0
Operating leases, future minimum lease payments due		38,800,000
Barges and Rail Cars [Member] | Georgia Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		25,000,000
Leasing commitment, 2014		20,000,000
Leasing commitment, 2015		14,000,000
Leasing commitment, 2016		8,000,000
Leasing commitment, 2017		5,000,000
Leasing commitment, 2018 and thereafter		2,000,000
Operating leases, future minimum lease payments due		74,000,000
Barges and Rail Cars [Member] | Alabama Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Operating Leases, Rent Expense		19,000,000		18,000,000	20,000,000
Barges and Rail Cars [Member] | Plant Scholz [Member] | Gulf Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2014		2,400,000
Leasing commitment, 2015		2,400,000
Barges and Rail Cars [Member] | Plants Crist and Smith [Member] | Gulf Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2014		13,000,000
Leasing commitment, 2015		13,000,000
Other Capital Lease Payments [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		42,000,000
Leasing commitment, 2014		38,000,000
Leasing commitment, 2015		29,000,000
Leasing commitment, 2016		26,000,000
Leasing commitment, 2017		21,000,000
Leasing commitment, 2018 and thereafter		73,000,000
Operating leases, future minimum lease payments due		229,000,000
Other Capital Lease Payments [Member] | Gulf Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		300,000
Leasing commitment, 2014		300,000
Leasing commitment, 2015		100,000
Leasing commitment, 2016		100,000
Leasing commitment, 2017		100,000
Leasing commitment, 2018 and thereafter		0
Operating leases, future minimum lease payments due		900,000
Other Capital Lease Payments [Member] | Georgia Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		5,000,000
Leasing commitment, 2014		4,000,000
Leasing commitment, 2015		3,000,000
Leasing commitment, 2016		2,000,000
Leasing commitment, 2017		1,000,000
Leasing commitment, 2018 and thereafter		1,000,000
Operating leases, future minimum lease payments due		16,000,000
Fuel Handling Equipment [Member] | Mississippi Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		200,000
Leasing commitment, 2014		200,000
Leasing commitment, 2015		200,000
Operating Leases, Rent Expense		200,000		400,000	700,000
Barge Transportation [Member] | Mississippi Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		8,200,000
Leasing commitment, 2014		8,200,000
Leasing commitment, 2015		8,200,000
Operating Leases, Rent Expense		7,300,000		7,500,000	8,400,000
Plant Vogtle Nuclear Units One and Two [Member] | Georgia Power [Member]
Total estimated minimum long-term obligations
Purchase obligation, 2012		24,000,000
2013		19,000,000
2014		11,000,000
2015		11,000,000
2016		8,000,000
2017 and thereafter		69,000,000
Total		142,000,000
Captial Lease PPA [Member] | Georgia Power [Member]
Total estimated minimum long-term obligations
Purchase obligation, 2012		0
2013		0
2014		22,000,000
2015		22,000,000
2016		23,000,000
2017 and thereafter		301,000,000
Total		368,000,000
Operating Lease PPA [Member] | Georgia Power [Member]
Total estimated minimum long-term obligations
Purchase obligation, 2012		162,000,000
2013		165,000,000
2014		223,000,000
2015		240,000,000
2016		215,000,000
2017 and thereafter		2,448,000,000
Total		3,453,000,000
Plant Daniel [Member] | Barges and Rail Cars [Member] | Gulf Power [Member]
Estimated minimum lease payments for noncancelable operating leases
Leasing commitment, 2013		1,600,000
Leasing commitment, 2014		1,600,000
Leasing commitment, 2015		1,600,000
Leasing commitment, 2016		1,600,000
Leasing commitment, 2017		1,600,000
Fuel cost recovery clause		$ 3,600,000		$ 2,600,000	$ 3,500,000

[1] (1)Executory costs include items such as taxes, maintenance, and insurance (including the estimated profit thereon).

[2] (2)Calculated at the Company's incremental borrowing rate at the inception of the leases.

[3] (3)When the PPAs begin in 2015, the Company will recognize a capital lease asset and a capital lease obligation of $149 million, equal to the estimated fair value of the leased property.