Summary of Significant Accounting Policies - Textual (Details)		1 Months Ended	2 Months Ended	3 Months Ended								12 Months Ended
	Feb. 06, 2015 MW	Dec. 31, 2013 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) kWh Property	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Oct. 06, 2015 USD ($)	Dec. 31, 2010 USD ($)
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation		$ 2,018,000,000	$ 2,201,000,000	$ 3,759,000,000				$ 2,201,000,000				$ 3,759,000,000	$ 2,201,000,000	$ 2,018,000,000
Retail Revenues												14,987,000,000	15,550,000,000	14,541,000,000
Net income after dividends on preferred and preference stock				271,000,000	$ 959,000,000	$ 629,000,000	$ 508,000,000	283,000,000	$ 718,000,000	$ 611,000,000	$ 351,000,000	2,367,000,000	1,963,000,000	1,644,000,000
Unamortized Debt Issuance Expense		(139,000,000)	(202,000,000)	(241,000,000)				(202,000,000)				$ (241,000,000)	(202,000,000)	(139,000,000)
Maximum revenue from a single customer or industry												10.00%
Maximum percentage of uncollectible accounts												1.00%
Deferred tax assets			5,241,000,000	6,358,000,000				5,241,000,000				$ 6,358,000,000	5,241,000,000
Non-cash property additions recognized												844,000,000	528,000,000	411,000,000
Other Cost of Removal Obligations			1,215,000,000	1,162,000,000				1,215,000,000				1,162,000,000	1,215,000,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			24,059,000,000	24,253,000,000				24,059,000,000				24,253,000,000	24,059,000,000
Investment securities in the Funds			1,546,000,000	1,512,000,000				1,546,000,000				1,512,000,000	1,546,000,000
Proceeds from sale of securities held in external trust funds												1,400,000,000	913,000,000	1,000,000,000
Increase (Decrease) in fair value of securities related to nuclear decommissioning												$ 11,000,000	$ 98,000,000	$ 181,000,000
AFUDC, net of income taxes												12.80%	16.00%	15.00%
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity												$ 226,000,000	$ 245,000,000	$ 190,000,000
Cash payments for interest totaled												809,000,000	732,000,000	759,000,000
Net of amounts capitalized												124,000,000	111,000,000	92,000,000
Other Regulatory Assets Current			346,000,000	402,000,000				346,000,000				402,000,000	346,000,000
Other Regulatory Assets Deferred			4,334,000,000	4,989,000,000				4,334,000,000				$ 4,989,000,000	4,334,000,000
Original Maturities of Temporary Cash Investments												90 days
Plant acquisition adjustment			123,000,000	123,000,000				123,000,000				$ 123,000,000	123,000,000
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Leveraged lease agreement term												45 years
Plant Hatch [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated cost of decommissioning completion year												2075
Equity Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			886,000,000	817,000,000				886,000,000				$ 817,000,000	886,000,000
Debt Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			638,000,000	654,000,000				638,000,000				654,000,000	638,000,000
Other Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			19,000,000	38,000,000				19,000,000				38,000,000	19,000,000
Securities Held in Funds [Member] | Unrealized Loss [Member]
Summary of Significant Accounting Policies [Line Items]
Increase (Decrease) in fair value of securities related to nuclear decommissioning												$ 83,000,000
Securities Held in Funds [Member] | Unrealized Gain [Member]
Summary of Significant Accounting Policies [Line Items]
Increase (Decrease) in fair value of securities related to nuclear decommissioning													$ 19,000,000	$ 119,000,000
Utility Plant in Service [Member]
Summary of Significant Accounting Policies [Line Items]
Depreciation of cost of utility plant in service, composite straight-line rate												3.00%	3.10%	3.30%
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			23,500,000,000	23,700,000,000				23,500,000,000				$ 23,700,000,000	$ 23,500,000,000
Other Plant in Service [Member]
Summary of Significant Accounting Policies [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			533,000,000	510,000,000				533,000,000				$ 510,000,000	533,000,000
Other Plant in Service [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Plant in service, estimated useful lives												3 years
Other Plant in Service [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Plant in service, estimated useful lives												25 years
Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													488,000,000	$ 143,000,000
Alabama Power [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation		$ 730,000,000	829,000,000	1,448,000,000				829,000,000				$ 1,448,000,000	829,000,000	730,000,000
Retail Revenues												5,234,000,000	5,249,000,000	4,952,000,000
Net income after dividends on preferred and preference stock				121,000,000	295,000,000	200,000,000	169,000,000	119,000,000	282,000,000	173,000,000	187,000,000	785,000,000	761,000,000	712,000,000
Unamortized Debt Issuance Expense			(39,000,000)	(45,000,000)				(39,000,000)				$ (45,000,000)	(39,000,000)
Maximum revenue from a single customer or industry												10.00%
Maximum percentage of uncollectible accounts												1.00%
Deferred tax assets			1,141,000,000	1,511,000,000				1,141,000,000				$ 1,511,000,000	1,141,000,000
Number of Units for which Outage Operations and Maintenance Expenses Accrued | Property												2
Period Over which Deferred Costs are Being Amortized to Nuclear Operations and Maintenance Expenses												18 months
Other Cost of Removal Obligations			744,000,000	722,000,000				744,000,000				$ 722,000,000	744,000,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			8,522,000,000	8,736,000,000				8,522,000,000				8,736,000,000	8,522,000,000
Regulatory liabilities amortized			120,000,000
Decommissioning Fund Investments Net Of Foreign Currency			754,000,000	734,000,000				754,000,000				734,000,000	754,000,000
Investment securities in the Funds			$ 756,000,000	$ 737,000,000				$ 756,000,000				737,000,000	756,000,000
Proceeds from sale of securities held in external trust funds												438,000,000	244,000,000	279,000,000
Increase (Decrease) in fair value of securities related to nuclear decommissioning												$ 8,000,000	$ 54,000,000	$ 120,000,000
Significant assumption of inflation rate used to determine the costs for rate making												4.50%
Significant assumption of trust earnings rate used to determine the costs for rate making												7.00%
Composite rate used to determine allowance for funds used during construction		9.10%	8.80%	8.70%				8.80%				8.70%	8.80%	9.10%
AFUDC, net of income taxes												9.30%	7.90%	5.40%
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity												$ 60,000,000	$ 49,000,000	$ 32,000,000
Cash payments for interest totaled												250,000,000	231,000,000	243,000,000
Net of amounts capitalized												22,000,000	18,000,000	11,000,000
Other Regulatory Assets Current			$ 84,000,000	$ 115,000,000				$ 84,000,000				115,000,000	84,000,000
Other Regulatory Assets Deferred			1,063,000,000	1,114,000,000				1,063,000,000				$ 1,114,000,000	1,063,000,000
Original Maturities of Temporary Cash Investments												90 days
Plant acquisition adjustment			12,000,000	12,000,000				12,000,000				$ 12,000,000	12,000,000
Alabama Power [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Life of Related Property Over which Deferred Income Tax Liabilities are Amortized												50 years
Alabama Power [Member] | Equity Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			583,000,000	521,000,000				583,000,000				$ 521,000,000	583,000,000
Alabama Power [Member] | Debt Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			163,000,000	191,000,000				163,000,000				191,000,000	163,000,000
Alabama Power [Member] | Other Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			8,000,000	22,000,000				8,000,000				22,000,000	8,000,000
Alabama Power [Member] | Securities Held in Funds [Member]
Summary of Significant Accounting Policies [Line Items]
Increase (Decrease) in fair value of securities related to nuclear decommissioning													$ 19,000,000	$ 85,000,000
Alabama Power [Member] | Securities Held in Funds [Member] | Unrealized Gain [Member]
Summary of Significant Accounting Policies [Line Items]
Increase (Decrease) in fair value of securities related to nuclear decommissioning												$ 57,000,000
Alabama Power [Member] | Utility Plant in Service [Member]
Summary of Significant Accounting Policies [Line Items]
Depreciation of cost of utility plant in service, composite straight-line rate												2.90%	3.30%	3.20%
Alabama Power [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 438,000,000	$ 400,000,000	$ 340,000,000
Alabama Power [Member] | Southern Nuclear Operating Company, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												243,000,000	234,000,000	211,000,000
Alabama Power [Member] | Gulf Power [Member]
Summary of Significant Accounting Policies [Line Items]
Revenue Requirements Reimbursement												$ 14,000,000
Alabama Power [Member] | Plant Farley [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated cost of decommissioning completion year												2076
Alabama Power [Member] | Fuel Purchases [Member] | Mississippi Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 8,000,000	34,000,000	27,000,000
Alabama Power [Member] | Non-Fuel Expense [Member] | Mississippi Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												11,000,000	13,000,000	13,000,000
Mississippi Power [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation		$ 42,000,000	48,000,000	177,000,000				48,000,000				177,000,000	48,000,000	42,000,000
Retail Revenues												776,000,000	795,000,000	799,000,000
Net income after dividends on preferred and preference stock				(71,000,000)	(21,000,000)	49,000,000	35,000,000	(24,000,000)	(195,000,000)	62,000,000	(172,000,000)	(8,000,000)	(329,000,000)	$ (477,000,000)
Unamortized Debt Issuance Expense			(9,000,000)	(8,000,000)				(9,000,000)				$ (8,000,000)	(9,000,000)
Percentage Of Wholesale Customers To Operating Revenue												21.00%
Period Of Contract Cancellation Notices Of Wholesale Customers												10 years
Maximum revenue from a single customer or industry												10.00%
Maximum percentage of uncollectible accounts												1.00%
Deferred tax assets			1,251,000,000	1,400,000,000				1,251,000,000				$ 1,400,000,000	$ 1,251,000,000
Depreciation of cost of utility plant in service, composite straight-line rate												4.70%	3.30%	3.40%
Other Cost of Removal Obligations			166,000,000	165,000,000				166,000,000				$ 165,000,000	$ 166,000,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			$ 1,173,000,000	$ 1,262,000,000				$ 1,173,000,000				$ 1,262,000,000	$ 1,173,000,000
Composite rate used to determine allowance for funds used during construction		6.89%	6.91%	5.99%				6.91%				5.99%	6.91%	6.89%
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity												$ 110,000,000	$ 136,000,000	$ 122,000,000
Threshold above which actual damages are charged to the reserve				$ 50,000								50,000
Retail accrual per annual SRR rate		$ 3,000,000	$ 3,000,000	3,000,000				$ 3,000,000				3,000,000	3,000,000	3,000,000
Wholesale accrual per annual SRR rate		300,000	300,000	300,000				300,000				300,000	300,000	300,000
Cash payments for interest totaled												45,000,000	7,000,000	20,000,000
Net of amounts capitalized												66,000,000	69,000,000	54,000,000
PSC Approved Annual Property Damage Reserve Accrual															$ 3,000,000
Other Regulatory Assets Current			73,000,000	95,000,000				73,000,000				95,000,000	73,000,000
Other Regulatory Assets Deferred			385,000,000	525,000,000				385,000,000				$ 525,000,000	385,000,000
Original Maturities of Temporary Cash Investments												90 days
Plant acquisition adjustment			81,000,000	81,000,000				81,000,000				$ 81,000,000	81,000,000
Variable Interest Entity, Consolidated, Carrying Amount, Assets		21,000,000	21,000,000	21,000,000				21,000,000				21,000,000	21,000,000	21,000,000
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities		23,000,000	24,000,000	25,000,000				24,000,000				$ 25,000,000	24,000,000	23,000,000
Mississippi Power [Member] | Mississippi Public Service Commission [Member]
Summary of Significant Accounting Policies [Line Items]
Period To Agree On System Restoration Rider												3 years
Mississippi Power [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 295,000,000	259,000,000	205,000,000
Mississippi Power [Member] | Gulf Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 27,000,000	31,000,000	17,000,000
Mississippi Power [Member] | Property tax [Member]
Summary of Significant Accounting Policies [Line Items]
Amortization period of regulatory assets and liabilities												12 months
Mississippi Power [Member] | Kemper IGCC [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation				11,000,000								$ 11,000,000
Grants expected to be received from Department of Energy				25,000,000								25,000,000				$ 270,000,000
Grants received from Department of Energy												245,000,000
Regulatory asset				120,000,000								120,000,000
Other Regulatory Assets Current				96,000,000								96,000,000
Other Regulatory Assets Deferred				195,000,000								$ 195,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Amortization period of regulatory assets and liabilities												2 years
Mississippi Power [Member] | Kemper IGCC [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Amortization period of regulatory assets and liabilities												10 years
Mississippi Power [Member] | Fuel Purchases [Member] | Alabama Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 8,000,000	34,000,000	27,000,000
Mississippi Power [Member] | Non-Fuel Expense [Member] | Alabama Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												11,000,000	13,000,000	13,000,000
Georgia Power [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation		$ 1,222,000,000	1,255,000,000	1,916,000,000				1,255,000,000				1,916,000,000	1,255,000,000	1,222,000,000
Retail Revenues												7,727,000,000	8,240,000,000	7,620,000,000
Net income after dividends on preferred and preference stock				196,000,000	551,000,000	277,000,000	236,000,000	123,000,000	525,000,000	311,000,000	266,000,000	1,260,000,000	1,225,000,000	$ 1,174,000,000
Unamortized Debt Issuance Expense			(124,000,000)	(118,000,000)				(124,000,000)				$ (118,000,000)	(124,000,000)
Maximum revenue from a single customer or industry												10.00%
Maximum percentage of uncollectible accounts												1.00%
Deferred tax assets			1,736,000,000	2,017,000,000				1,736,000,000				$ 2,017,000,000	$ 1,736,000,000
Refueling cycles for Alabama Power and Georgia Power, minimum months												18 months
Refueling cycles for Alabama Power and Georgia Power, maximum months												24 months
Depreciation of cost of utility plant in service, composite straight-line rate												2.70%	2.70%	3.00%
Other Cost of Removal Obligations			46,000,000	16,000,000				46,000,000				$ 16,000,000	$ 46,000,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			11,222,000,000	10,903,000,000				11,222,000,000				10,903,000,000	11,222,000,000
Regulatory liabilities amortized												$ 14,000,000	14,000,000	$ 31,000,000
Asset Retirement Obligation, Period Of Update Cycle												3 years
Fair market value of fund's securities on loan under the Funds' managers' securities lending program			51,000,000	76,000,000				51,000,000				$ 76,000,000	51,000,000
Fair value of collateral received			52,000,000	78,000,000				52,000,000				78,000,000	52,000,000
Decommissioning Fund Investments Net Of Foreign Currency			789,000,000	775,000,000				789,000,000				775,000,000	789,000,000
Investment securities in the Funds			$ 789,000,000	$ 775,000,000				$ 789,000,000				775,000,000	789,000,000
Increase (Decrease) in fair value of securities related to nuclear decommissioning												$ 3,000,000	$ 44,000,000	$ 61,000,000
Significant assumption of inflation rate used to determine the costs for rate making												2.40%
Significant assumption of trust earnings rate used to determine the costs for rate making												4.40%
Composite rate used to determine allowance for funds used during construction		5.30%	5.60%	6.50%				5.60%				6.50%	5.60%	5.30%
AFUDC capitalized												$ 56,000,000	$ 62,000,000	$ 44,000,000
AFUDC, net of income taxes												3.90%	4.60%	3.30%
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity												$ 40,000,000	$ 45,000,000	$ 30,000,000
Cash payments for interest totaled												353,000,000	319,000,000	344,000,000
Net of amounts capitalized												16,000,000	18,000,000	14,000,000
Accrual Under Alternate Rate Plan												30,000,000
Other Regulatory Assets Current			$ 136,000,000	$ 123,000,000				$ 136,000,000				123,000,000	136,000,000
Other Regulatory Assets Deferred			1,753,000,000	2,152,000,000				1,753,000,000				2,152,000,000	1,753,000,000
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation				29,000,000								$ 29,000,000
Original Maturities of Temporary Cash Investments												90 days
Amortization period of other cost of removal obligations												12 months
Plant acquisition adjustment			28,000,000	28,000,000				28,000,000				$ 28,000,000	28,000,000
Georgia Power [Member] | Unrealized Losses [Member]
Summary of Significant Accounting Policies [Line Items]
Increase (Decrease) in fair value of securities related to nuclear decommissioning														34,000,000
Georgia Power [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Life of Related Property Over which Deferred Income Tax Liabilities are Amortized												70 years
Georgia Power [Member] | Plant Hatch [Member]
Summary of Significant Accounting Policies [Line Items]
Amount expensed for rate making purpose														4,000,000
Estimated cost of decommissioning completion year												2075
Georgia Power [Member] | Plant Vogtle [Member]
Summary of Significant Accounting Policies [Line Items]
Amount expensed for rate making purpose														2,000,000
Georgia Power [Member] | Securities Investment [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds		$ 705,000,000	669,000,000	980,000,000				669,000,000				$ 980,000,000	669,000,000	705,000,000
Georgia Power [Member] | Equity Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			303,000,000	296,000,000				303,000,000				296,000,000	303,000,000
Georgia Power [Member] | Debt Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			475,000,000	463,000,000				475,000,000				463,000,000	475,000,000
Georgia Power [Member] | Other Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Investment securities in the Funds			11,000,000	16,000,000				11,000,000				16,000,000	11,000,000
Georgia Power [Member] | Securities Held in Funds [Member]
Summary of Significant Accounting Policies [Line Items]
Increase (Decrease) in fair value of securities related to nuclear decommissioning												26,000,000	0
Georgia Power [Member] | Southern Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												179,000,000	144,000,000	136,000,000
Prepaid capacity expenses			15,000,000	$ 15,000,000				15,000,000				15,000,000	15,000,000
Georgia Power [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												585,000,000	555,000,000	504,000,000
Georgia Power [Member] | Southern Nuclear Operating Company, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 681,000,000	643,000,000	555,000,000
Georgia Power [Member] | Gulf Power [Member] | Plant Scherer Unit 3 [Member]
Summary of Significant Accounting Policies [Line Items]
Gulf Power agreement, percentage reimbursement of non-fuel expenses				25.00%								25.00%
Georgia Power [Member] | Other regulatory assets current [Member]
Summary of Significant Accounting Policies [Line Items]
Environmental Regulatory Assets				$ 2,000,000								$ 2,000,000
Georgia Power [Member] | Other regulatory assets deferred [Member]
Summary of Significant Accounting Policies [Line Items]
Environmental Regulatory Assets				30,000,000								30,000,000
Georgia Power [Member] | Property damage reserves-liability [Member]
Summary of Significant Accounting Policies [Line Items]
Regulatory asset			98,000,000	92,000,000				98,000,000				92,000,000	98,000,000
Other Regulatory Assets Current			30,000,000	30,000,000				30,000,000				30,000,000	30,000,000
Other Regulatory Assets Deferred			68,000,000	62,000,000				68,000,000				62,000,000	68,000,000
Georgia Power [Member] | Non-Fuel Expense [Member] | Gulf Power [Member] | Plant Scherer Unit 3 [Member]
Summary of Significant Accounting Policies [Line Items]
Gulf Power agreement, reimbursement of non-fuel expenses												12,000,000	9,000,000	10,000,000
Southern Power [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation		4,000,000	13,000,000	21,000,000				13,000,000				21,000,000	13,000,000	4,000,000
Net income after dividends on preferred and preference stock				34,000,000	102,000,000	46,000,000	33,000,000	44,000,000	64,000,000	31,000,000	33,000,000
Unamortized Debt Issuance Expense			(11,000,000)	(19,000,000)				(11,000,000)				(19,000,000)	(11,000,000)
Deferred tax assets			481,000,000	794,000,000				481,000,000				$ 794,000,000	481,000,000
Reduction in tax basis of assets												50.00%
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			1,035,000,000	1,248,000,000				1,035,000,000				$ 1,248,000,000	1,035,000,000
Plant In Service Depreciated On A Units Of Production Basis			470,000,000	485,000,000				470,000,000				485,000,000	470,000,000
Cash payments for interest totaled												74,000,000	85,000,000	60,000,000
Net of amounts capitalized												14,000,000	0	9,000,000
Restricted Cash and Cash Equivalents, Noncurrent				5,000,000								$ 5,000,000
Original Maturities of Temporary Cash Investments												90 days
Period Of Reimbursement Of Transmission Costs												5 years
Amortization of Intangible Assets												$ 3,000,000	3,000,000	3,000,000
Average term of PPAs												20 years
Deferred project development costs			11,000,000	11,000,000				11,000,000				$ 11,000,000	11,000,000
Southern Power [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Plant in service, estimated useful lives												30 years
Southern Power [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Plant in service, estimated useful lives												45 years
Southern Power [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 146,000,000	126,000,000	118,000,000
Southern Power [Member] | Operations and Maintenance Expense [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												138,000,000	125,000,000	114,000,000
Southern Power [Member] | Electric Transmission [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 11,000,000	$ 7,000,000	$ 8,000,000
Southern Power [Member] | Florida Power and Light [Member] | Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member]
Summary of Significant Accounting Policies [Line Items]
Maximum revenue from a single customer or industry												10.70%	9.70%	10.70%
Southern Power [Member] | Georgia Power [Member] | Sales Revenue, Goods, Net [Member] | Customer Concentration Risk [Member]
Summary of Significant Accounting Policies [Line Items]
Maximum revenue from a single customer or industry												15.80%	10.10%	11.80%
Southern Power [Member] | Purchased Power from Affiliates [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 219,000,000	$ 153,000,000	$ 150,000,000
Southern Power [Member] | Operating Lease PPA [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												109,000,000	75,000,000	69,000,000
Gulf Power [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation		$ 16,000,000	17,000,000	130,000,000				17,000,000				130,000,000	17,000,000	16,000,000
Retail Revenues												1,249,000,000	1,267,000,000	1,170,000,000
Net income after dividends on preferred and preference stock				28,000,000	$ 48,000,000	35,000,000	$ 37,000,000	23,000,000	$ 46,000,000	$ 34,000,000	$ 37,000,000	148,000,000	140,000,000	$ 124,000,000
Unamortized Debt Issuance Expense			(8,000,000)	(8,000,000)				(8,000,000)				$ (8,000,000)	(8,000,000)
Projected fuel cost over or under recovery threshold, as a percentage of projected fuel revenue												10.00%
Maximum revenue from a single customer or industry												10.00%
Maximum percentage of uncollectible accounts												1.00%
Deferred tax assets			171,000,000	216,000,000				171,000,000				$ 216,000,000	$ 171,000,000
Depreciation of cost of utility plant in service, composite straight-line rate												3.50%	3.60%	3.60%
Other Cost of Removal Obligations			235,000,000	233,000,000				235,000,000				$ 233,000,000	$ 235,000,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			$ 1,296,000,000	$ 1,296,000,000				$ 1,296,000,000				$ 1,296,000,000	$ 1,296,000,000
Composite rate used to determine allowance for funds used during construction		6.26%	5.73%	5.73%				5.73%				5.73%	5.73%	6.26%
AFUDC, net of income taxes												10.80%	10.93%	6.87%
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity												$ 13,000,000	$ 12,000,000	$ 6,000,000
Cash payments for interest totaled												52,000,000	48,000,000	53,000,000
Net of amounts capitalized												6,000,000	5,000,000	3,000,000
PSC Approved Annual Property Damage Reserve Accrual				$ 3,500,000								3,500,000
Threshold above which additional property damage reserves are authorized by PSC				3,500,000								3,500,000
Increase in accrued property damage costs												3,500,000	3,500,000	3,500,000
Accrued reserves			$ 35,000,000	38,000,000				$ 35,000,000				$ 38,000,000	35,000,000
Recovery Period For Natural Disaster Reserve Costs												60 days
Cumulative damage costs limit under PSC order												$ 100,000,000
PSC approved annual uninsured injuries and damages accrual				1,600,000								1,600,000
Threshold above which additional uninsured injuries and damages accruals are authorized by PSC				1,600,000								1,600,000
Reserve for losses and loss adjustment expenses			4,000,000	0				4,000,000				0	4,000,000
Other Regulatory Assets Current			74,000,000	90,000,000				74,000,000				90,000,000	74,000,000
Other Regulatory Assets Deferred			416,000,000	427,000,000				416,000,000				427,000,000	416,000,000
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation				46,000,000								$ 46,000,000
Original Maturities of Temporary Cash Investments												90 days
Plant acquisition adjustment			2,000,000	2,000,000				2,000,000				$ 2,000,000	2,000,000
Net Regulatory Assets				1,700,000								$ 1,700,000
Gulf Power [Member] | Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Projected fuel cost over or under recovery threshold, as a percentage of projected fuel revenue												10.00%
PSC approved target level for property damage reserve				48,000,000								$ 48,000,000
Gulf Power [Member] | Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
PSC approved target level for property damage reserve				55,000,000								55,000,000
Customer Surcharge Storm Recovery Costs												$ 4
Customer Surcharge Storm Recovery Capacity | kWh												1,000
PSC approved annual uninsured injuries and damages accrual				2,000,000.0								$ 2,000,000.0
Life of Related Property Over which Deferred Income Tax Liabilities are Amortized												65 years
Gulf Power [Member] | Georgia Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												$ 12,000,000	9,000,000	10,000,000
Gulf Power [Member] | Alabama Power [Member]
Summary of Significant Accounting Policies [Line Items]
Revenue Requirements Reimbursement												14,000,000	12,000,000	8,000,000
Gulf Power [Member] | Southern Company Services, Inc. [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												81,000,000	80,000,000	78,000,000
Gulf Power [Member] | Mississippi Power [Member]
Summary of Significant Accounting Policies [Line Items]
Related Party Transaction, Amounts of Transaction												27,000,000	31,000,000	17,000,000
Gulf Power [Member] | Current Liabilities [Member]
Summary of Significant Accounting Policies [Line Items]
Reserve for losses and loss adjustment expenses			1,600,000	1,600,000				1,600,000				1,600,000	1,600,000
Gulf Power [Member] | Deferred Credits and Other Liabilities [Member]
Summary of Significant Accounting Policies [Line Items]
Reserve for losses and loss adjustment expenses			2,400,000	100,000				2,400,000				100,000	2,400,000
Gulf Power [Member] | Plant Smith Units 1 and 2 [Member]
Summary of Significant Accounting Policies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units | MW	357
Net Book Value Of Planned Units Retirements				62,000,000								62,000,000
Gulf Power [Member] | Plant Scholz [Member]
Summary of Significant Accounting Policies [Line Items]
Asset Retirement Obligation				29,000,000								$ 29,000,000
Alabama Power and Georgia Power [Member]
Summary of Significant Accounting Policies [Line Items]
Refueling cycles for Alabama Power and Georgia Power, minimum months												18 months
Refueling cycles for Alabama Power and Georgia Power, maximum months												24 months
Traditional Operating Companies [Member]
Summary of Significant Accounting Policies [Line Items]
Accrued reserves		$ 28,000,000	$ 40,000,000	40,000,000				$ 40,000,000				$ 40,000,000	40,000,000	28,000,000
Capital Lease Obligations [Member]
Summary of Significant Accounting Policies [Line Items]
Non-cash property additions recognized												13,000,000	25,000,000	$ 107,000,000
Settlement Agreement [Member] | Gulf Power [Member]
Summary of Significant Accounting Policies [Line Items]
Other Cost of Removal Obligations				62,500,000								62,500,000
Environmental Remediation Reserve [Member] | Georgia Power [Member]
Summary of Significant Accounting Policies [Line Items]
Costs recovered annually under rate plan		$ 2,000,000										3,000,000
Retail [Member]
Summary of Significant Accounting Policies [Line Items]
Proposed Property Damage Reserve				63,000,000								63,000,000
Wholesale [Member]
Summary of Significant Accounting Policies [Line Items]
Proposed Property Damage Reserve				1,000,000								1,000,000
Scenario, Plan [Member] | Alabama Power [Member] | Gulf Power [Member]
Summary of Significant Accounting Policies [Line Items]
Revenue Requirements Reimbursement												12,000,000
Scenario, Plan [Member] | Gulf Power [Member] | Alabama Power [Member]
Summary of Significant Accounting Policies [Line Items]
Revenue Requirements Reimbursement												12,000,000
Restatement Adjustment [Member] | Georgia Power [Member]
Summary of Significant Accounting Policies [Line Items]
Retail Revenues						(75,000,000)
Net income after dividends on preferred and preference stock						$ (47,000,000)
Investment Tax And Other Credit Carryforward [Member] | Georgia Power [Member]
Summary of Significant Accounting Policies [Line Items]
Deferred tax assets				$ 318,000,000								$ 318,000,000
Deferred Charges Related To Income Taxes, Current [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													506,000,000
Deferred Charges Related To Income Taxes, Current [Member] | Other Noncurrent Assets [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													18,000,000
Deferred Charges Related To Income Taxes, Current [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													488,000,000
Deferred Charges Related To Income Taxes, Current [Member] | Georgia Power [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													34,000,000
Prepaid Expense, Current [Member] | Alabama Power [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													20,000,000
Prepaid Expense, Current [Member] | Mississippi Power [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													121,000,000
Prepaid Expense, Current [Member] | Mississippi Power [Member] | Other Noncurrent Assets [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													16,000,000
Prepaid Expense, Current [Member] | Mississippi Power [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													105,000,000
Prepaid Expense, Current [Member] | Southern Power [Member] | Other Noncurrent Assets [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													306,000,000
Prepaid Expense, Current [Member] | Gulf Power [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													3,000,000
Accrued Income Taxes, Current [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													2,000,000
Accrued Income Taxes, Current [Member] | Alabama Power [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													2,000,000
Accrued Income Taxes, Current [Member] | Southern Power [Member] | Deferred Tax Liability, Noncurrent [Member]
Summary of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment													$ 2,000,000