Commitments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Recorded Unconditional Purchase Obligation [Line Items]
Fuel expense	$ 6,005,000,000		$ 5,510,000,000	$ 5,057,000,000
Expense Under Purchase Power Agreements Accounted For As Operating Leases	198,000,000		157,000,000	171,000,000
Operating Leases, Rent Expense	118,000,000		123,000,000	155,000,000
Leasing commitment, 2015	100,000,000
Leasing commitment, 2016	89,000,000
Leasing commitment, 2017	65,000,000
Leasing commitment, 2018	44,000,000
Leasing commitment, 2019	29,000,000
Leasing commitment, 2020 and thereafter	248,000,000
Operating leases, future minimum lease payments due	575,000,000
Senior Notes	18,200,000,000		17,300,000,000
Barges and Rail Cars [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Leasing commitment, 2015	50,000,000
Leasing commitment, 2016	41,000,000
Leasing commitment, 2017	18,000,000
Leasing commitment, 2018	9,000,000
Leasing commitment, 2019	6,000,000
Leasing commitment, 2020 and thereafter	20,000,000
Operating leases, future minimum lease payments due	144,000,000
Alabama Power and Georgia Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating leases, future minimum lease payments due	53,000,000
Alabama Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel expense	1,605,000,000		1,631,000,000	1,503,000,000
Expense Under Purchase Power Agreements Accounted For As Operating Leases	37,000,000		30,000,000	33,000,000
Jointly Owned Utility Plant, Proportionate Ownership Share	14.00%
Operating Leases, Rent Expense	18,000,000		21,000,000	24,000,000
Leasing commitment, 2015	16,000,000
Leasing commitment, 2016	14,000,000
Leasing commitment, 2017	10,000,000
Leasing commitment, 2018	6,000,000
Leasing commitment, 2019	5,000,000
Leasing commitment, 2020 and thereafter	17,000,000
Operating leases, future minimum lease payments due	68,000,000
Long-term pollution control bonds	1,200,000,000		1,200,000,000
Alabama Power [Member] | Barges and Rail Cars [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating Leases, Rent Expense	14,000,000		18,000,000	19,000,000
Alabama Power [Member] | Residual Value, Leased Property [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Leasing commitment, 2015	5,000,000
Leasing commitment, 2016	4,000,000
Leasing commitment, 2019	0
Leasing commitment, 2020 and thereafter	12,000,000
Georgia Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Capital Leases, Future Minimum Payments, Lesser Of Fair Value and Present Value	149,000,000
Fuel expense	2,547,000,000		2,307,000,000	2,051,000,000
Capacity Payments	19,000,000		27,000,000	50,000,000
Deferred capacity expense	167,000,000		162,000,000	169,000,000
Operating Leases, Rent Expense	28,000,000		32,000,000	34,000,000
Percentage Of Minimum Lease Payments	100.00%
Leasing commitment, 2015	25,000,000
Leasing commitment, 2016	20,000,000
Leasing commitment, 2017	16,000,000
Leasing commitment, 2018	10,000,000
Leasing commitment, 2019	5,000,000
Leasing commitment, 2020 and thereafter	14,000,000
Operating leases, future minimum lease payments due	90,000,000
Long-term pollution control bonds	1,600,000,000		1,700,000,000
Senior Notes			6,900,000,000
Period Of Service For Gas Transportation Supplier	1 year
Guarantor Obligations, Maximum Exposure, Undiscounted	43,000,000
Georgia Power [Member] | Plant McIntosh [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Period Of Service For Gas Transportation Supplier	15 years
Georgia Power [Member] | MEAG Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	5.00%
Georgia Power [Member] | Alabama Power [Member] | Payment Guarantee [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Long-term pollution control bonds	25,000,000
Georgia Power [Member] | Alabama Power [Member] | Financial Guarantee [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Senior Notes	100,000,000
Georgia Power [Member] | Barges and Rail Cars [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Leasing commitment, 2015	18,000,000
Leasing commitment, 2016	13,000,000
Leasing commitment, 2017	9,000,000
Leasing commitment, 2018	4,000,000
Leasing commitment, 2019	1,000,000
Leasing commitment, 2020 and thereafter	3,000,000
Operating leases, future minimum lease payments due	48,000,000
Georgia Power [Member] | Residual Value, Leased Property [Member] | 2018 [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating leases, future minimum lease payments due	32,000,000
Gulf Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel expense	604,641,000		532,791,000	544,936,000
Expense Under Purchase Power Agreements Accounted For As Operating Leases	49,500,000		21,300,000	24,600,000
Deferred capacity expense	163,077,000		180,149,000
Operating Leases, Rent Expense	15,000,000		18,000,000	20,100,000
Leasing commitment, 2015	15,200,000
Leasing commitment, 2016	15,100,000
Leasing commitment, 2017	1,500,000
Operating leases, future minimum lease payments due	31,800,000
Long-term pollution control bonds	309,000,000		296,000,000
Senior Notes	1,070,000,000		945,000,000
Gulf Power [Member] | Plant Daniel [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Long-term pollution control bonds	41,000,000
Gulf Power [Member] | Barges and Rail Cars [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Leasing commitment, 2015	15,100,000
Leasing commitment, 2016	15,000,000
Leasing commitment, 2017	1,400,000
Operating leases, future minimum lease payments due	31,500,000
Gulf Power [Member] | Barges and Rail Cars [Member] | Plant Daniel [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel cost recovery clause	2,800,000		3,100,000	3,600,000
Leasing commitment, 2015	1,600,000
Leasing commitment, 2016	1,600,000
Leasing commitment, 2017	1,600,000
Leasing commitment, 2018	0
Leasing commitment, 2020 and thereafter	0
Mississippi Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel expense	573,936,000		491,250,000	411,226,000
Term of Management Fee Contract	40 years
Management fee	38,400,000
Operating Leases, Rent Expense	12,700,000		10,100,000	11,100,000
Number of Railcars Used Under Operating Lease	229
Company's share of the leases	50.00%
Fuel cost recovery clause	4,900,000		3,100,000	3,600,000
Long-term pollution control bonds	82,700,000		82,700,000
Senior Notes	1,100,000,000		1,100,000,000
Mississippi Power [Member] | Plant Daniel [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Company's share of the leases	50.00%
Mississippi Power [Member] | Plant Watson [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Company's share of the leases	100.00%
Mississippi Power [Member] | Barges and Rail Cars [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Average leasing commitment, 2015	1,600,000
Average leasing commitment, 2016	1,600,000
Average leasing commitment, 2017	1,600,000
Average leasing commitment, 2018	0
Mississippi Power [Member] | Fuel Handling Equipment [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating Leases, Rent Expense	200,000		200,000	200,000
Leasing commitment, 2015	100,000
Mississippi Power [Member] | Barge Transportation [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating Leases, Rent Expense	7,500,000		6,700,000	7,300,000
Leasing commitment, 2015	1,800,000
Southern Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Fuel expense	596,319,000		473,805,000	426,257,000
Operating Leases, Rent Expense	4,000,000		1,900,000	800,000
Leasing commitment, 2015	4,500,000
Leasing commitment, 2016	4,500,000
Leasing commitment, 2017	4,600,000
Leasing commitment, 2018	4,600,000
Leasing commitment, 2019	4,700,000
Leasing commitment, 2020 and thereafter	157,200,000
Senior Notes	1,600,000,000
Non-Affiliate Operating Lease PPA [Member] | Georgia Power [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Biomass PPAs Amount	1,100,000,000
Leasing commitment, 2015	114,000,000	[1]
Leasing commitment, 2016	117,000,000	[1]
Leasing commitment, 2017	146,000,000	[1]
Leasing commitment, 2018	150,000,000	[1]
Leasing commitment, 2019	152,000,000	[1]
Leasing commitment, 2020 and thereafter	1,572,000,000	[1]
Operating leases, future minimum lease payments due	$ 2,251,000,000	[1]

[1] A total of $1.1 billion of biomass PPAs included under the non-affiliate operating leases is contingent upon the counterparties meeting specified contract dates for commercial operation and may change as a result of regulatory action.