Summary of Significant Accounting Policies - Textual (Details) (USD $)	12 Months Ended						12 Months Ended								12 Months Ended										12 Months Ended							12 Months Ended				12 Months Ended						3 Months Ended		12 Months Ended											12 Months Ended																12 Months Ended			12 Months Ended											12 Months Ended											12 Months Ended																																					12 Months Ended																		12 Months Ended																				12 Months Ended																					12 Months Ended																	12 Months Ended				0 Months Ended	12 Months Ended				12 Months Ended		0 Months Ended	12 Months Ended									0 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2012 Plant Hatch [Member]	Dec. 31, 2012 Plant Vogtle Nuclear Units One and Two [Member]	Dec. 31, 2009 Plant Vogtle [Member]	Dec. 31, 2012 Plant Vogtle [Member]	Dec. 31, 2012 Equity Securities [Member]	Dec. 31, 2011 Equity Securities [Member]	Dec. 31, 2012 Debt Securities [Member]	Dec. 31, 2011 Debt Securities [Member]	Dec. 31, 2012 Other Securities [Member]	Dec. 31, 2011 Other Securities [Member]	Dec. 31, 2010 Securities Held in Funds [Member]	Dec. 31, 2012 Securities Held in Funds [Member] Realized Gain [Member]	Dec. 31, 2011 Securities Held in Funds [Member] Realized Gain [Member]	Dec. 31, 2012 Securities Held in Funds [Member] Unrealized Gain [Member]	Dec. 31, 2011 Securities Held in Funds [Member] Unrealized Losses [Member]	Dec. 31, 2012 Utility Plant in Service [Member]	Dec. 31, 2011 Utility Plant in Service [Member]	Dec. 31, 2010 Utility Plant in Service [Member]	Dec. 31, 2012 Other Plant in Service [Member]	Dec. 31, 2011 Other Plant in Service [Member]	Dec. 31, 2012 Other Plant in Service [Member] Minimum [Member]	Dec. 31, 2012 Other Plant in Service [Member] Maximum [Member]	Dec. 31, 2012 Southern Power [Member]	Dec. 31, 2011 Southern Power [Member]	Dec. 31, 2010 Southern Power [Member]	Sep. 30, 2012 Southern Power [Member]	Jun. 30, 2012 Southern Power [Member]	Dec. 31, 2012 Southern Power [Member] Minimum [Member]	Dec. 31, 2012 Southern Power [Member] Maximum [Member]	Dec. 31, 2012 Southern Power [Member] Southern Renewable Energy, Inc. [Member]	Dec. 31, 2012 Southern Power [Member] Turner Renewable Energy [Member]	Dec. 31, 2012 Gulf Power [Member]	Dec. 31, 2011 Gulf Power [Member]	Dec. 31, 2010 Gulf Power [Member]	Dec. 31, 2012 Gulf Power [Member] Minimum [Member]	Dec. 31, 2012 Gulf Power [Member] Maximum [Member]	Dec. 31, 2012 Gulf Power [Member] Plant Scherer Unit 3 [Member]	Jun. 30, 2012 Alabama Power [Member]	Sep. 30, 2011 Alabama Power [Member]	Dec. 31, 2012 Alabama Power [Member]	Dec. 31, 2011 Alabama Power [Member]	Dec. 31, 2010 Alabama Power [Member]	Dec. 31, 2012 Alabama Power [Member] Maximum [Member]	Dec. 31, 2012 Alabama Power [Member] SEGCO [Member]	Dec. 31, 2012 Alabama Power [Member] Equity Securities [Member]	Dec. 31, 2011 Alabama Power [Member] Equity Securities [Member]	Dec. 31, 2012 Alabama Power [Member] Debt Securities [Member]	Dec. 31, 2011 Alabama Power [Member] Debt Securities [Member]	Dec. 31, 2012 Alabama Power [Member] Other Securities [Member]	Dec. 31, 2011 Alabama Power [Member] Other Securities [Member]	Dec. 31, 2011 Alabama Power [Member] Securities Held in Funds [Member]	Dec. 31, 2010 Alabama Power [Member] Securities Held in Funds [Member]	Dec. 31, 2012 Alabama Power [Member] Securities Held in Funds [Member] Realized Gain [Member]	Dec. 31, 2011 Alabama Power [Member] Securities Held in Funds [Member] Realized Gain [Member]	Dec. 31, 2012 Alabama Power [Member] Securities Held in Funds [Member] Unrealized Gain [Member]	Dec. 31, 2012 Alabama Power [Member] Utility Plant in Service [Member]	Dec. 31, 2011 Alabama Power [Member] Utility Plant in Service [Member]	Dec. 31, 2010 Alabama Power [Member] Utility Plant in Service [Member]	Dec. 31, 2012 Georgia Power [Member]	Dec. 31, 2011 Georgia Power [Member]	Dec. 31, 2010 Georgia Power [Member]	Dec. 31, 2012 Georgia Power [Member] Unrealized Losses [Member]	Dec. 31, 2011 Georgia Power [Member] Unrealized Losses [Member]	Dec. 31, 2010 Georgia Power [Member] Unrealized Losses [Member]	Dec. 31, 2012 Georgia Power [Member] Maximum [Member]	Dec. 31, 2012 Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2012 Georgia Power [Member] Plant McIntosh [Member]	Dec. 31, 2012 Georgia Power [Member] Plant Hatch [Member]	Dec. 31, 2012 Georgia Power [Member] Plant Vogtle Nuclear Units One and Two [Member]	Dec. 31, 2009 Georgia Power [Member] Plant Vogtle [Member]	Dec. 31, 2012 Georgia Power [Member] Plant Vogtle [Member]	Dec. 31, 2012 Georgia Power [Member] Securities Investment [Member]	Dec. 31, 2011 Georgia Power [Member] Securities Investment [Member]	Dec. 31, 2010 Georgia Power [Member] Securities Investment [Member]	Dec. 31, 2012 Georgia Power [Member] Equity Securities [Member]	Dec. 31, 2011 Georgia Power [Member] Equity Securities [Member]	Dec. 31, 2012 Georgia Power [Member] Debt Securities [Member]	Dec. 31, 2011 Georgia Power [Member] Debt Securities [Member]	Dec. 31, 2012 Georgia Power [Member] Other Securities [Member]	Dec. 31, 2011 Georgia Power [Member] Other Securities [Member]	Dec. 31, 2012 Alabama Power and Georgia Power [Member]	Dec. 31, 2012 Mississippi Power [Member]	Dec. 31, 2011 Mississippi Power [Member]	Dec. 31, 2010 Mississippi Power [Member]	Dec. 31, 2001 Mississippi Power [Member]	Jan. 18, 2013 Mississippi Power [Member]	Nov. 15, 2011 Mississippi Power [Member]	Oct. 20, 2011 Mississippi Power [Member]	Nov. 30, 2010 Mississippi Power [Member]	Dec. 31, 2012 Traditional Operating Companies [Member]	Dec. 31, 2011 Traditional Operating Companies [Member]	Dec. 31, 2012 Georgia Power [Member] Gulf Power [Member]	Dec. 31, 2011 Georgia Power [Member] Gulf Power [Member]	Dec. 31, 2010 Georgia Power [Member] Gulf Power [Member]	Dec. 31, 2012 Alabama Power [Member] Gulf Power [Member]	Dec. 31, 2011 Alabama Power [Member] Gulf Power [Member]	Dec. 31, 2012 Southern Power [Member] Gulf Power [Member] MW	Dec. 31, 2012 Southern Power [Member] Georgia Power [Member]	Dec. 31, 2011 Southern Power [Member] Georgia Power [Member]	Dec. 31, 2010 Southern Power [Member] Georgia Power [Member]	Dec. 31, 2012 Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2011 Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2010 Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2012 Southern Company Services, Inc. [Member] Gulf Power [Member]	Dec. 31, 2011 Southern Company Services, Inc. [Member] Gulf Power [Member]	Dec. 31, 2010 Southern Company Services, Inc. [Member] Gulf Power [Member]	Dec. 31, 2012 Southern Company Services, Inc. [Member] Alabama Power [Member]	Dec. 31, 2011 Southern Company Services, Inc. [Member] Alabama Power [Member]	Dec. 31, 2010 Southern Company Services, Inc. [Member] Alabama Power [Member]	Dec. 31, 2012 Southern Company Services, Inc. [Member] Georgia Power [Member]	Dec. 31, 2011 Southern Company Services, Inc. [Member] Georgia Power [Member]	Dec. 31, 2010 Southern Company Services, Inc. [Member] Georgia Power [Member]	Dec. 31, 2012 Southern Company Services, Inc. [Member] Mississippi Power [Member]	Dec. 31, 2011 Southern Company Services, Inc. [Member] Mississippi Power [Member]	Dec. 31, 2010 Southern Company Services, Inc. [Member] Mississippi Power [Member]	Dec. 31, 2012 Southern Nuclear Operating Company, Inc. [Member] Alabama Power [Member]	Dec. 31, 2011 Southern Nuclear Operating Company, Inc. [Member] Alabama Power [Member]	Dec. 31, 2010 Southern Nuclear Operating Company, Inc. [Member] Alabama Power [Member]	Dec. 31, 2012 Southern Nuclear Operating Company, Inc. [Member] Georgia Power [Member]	Dec. 31, 2011 Southern Nuclear Operating Company, Inc. [Member] Georgia Power [Member]	Dec. 31, 2010 Southern Nuclear Operating Company, Inc. [Member] Georgia Power [Member]	Dec. 31, 2012 Mississippi Power [Member] Gulf Power [Member]	Dec. 31, 2011 Mississippi Power [Member] Gulf Power [Member]	Dec. 31, 2010 Mississippi Power [Member] Gulf Power [Member]	Dec. 31, 2012 Gulf Power [Member] Alabama Power [Member]	Dec. 31, 2011 Gulf Power [Member] Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2010 Gulf Power [Member] Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2012 Gulf Power [Member] Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2012 Gulf Power [Member] Mississippi Power [Member]	Dec. 31, 2011 Gulf Power [Member] Mississippi Power [Member]	Dec. 31, 2010 Gulf Power [Member] Mississippi Power [Member]	Dec. 31, 2010 Purchased Power [Member] Southern Power [Member] Alabama Power [Member]	Dec. 31, 2010 Fuel Expense [Member] Southern Power [Member] Alabama Power [Member]	Dec. 31, 2012 Operations and Maintenance Expense [Member] Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2011 Operations and Maintenance Expense [Member] Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2010 Operations and Maintenance Expense [Member] Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2012 Deferred capacity revenues affiliated [Member] Southern Power [Member]	Dec. 31, 2011 Deferred capacity revenues affiliated [Member] Southern Power [Member]	Dec. 31, 2010 Deferred capacity revenues affiliated [Member] Southern Power [Member]	Dec. 31, 2012 Prepaid expenses and other regulatory liabilities [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2012 Other regulatory assets, current [Member] Georgia Power [Member]	Dec. 31, 2012 Other regulatory assets, deferred [Member] Georgia Power [Member]	Dec. 31, 2012 Current Liabilities [Member] Gulf Power [Member]	Dec. 31, 2011 Current Liabilities [Member] Gulf Power [Member]	Dec. 31, 2012 Deferred Credits and Other Liabilities [Member] Gulf Power [Member]	Dec. 31, 2011 Deferred Credits and Other Liabilities [Member] Gulf Power [Member]	Dec. 31, 2012 Property tax [Member] Mississippi Power [Member]		Dec. 31, 2011 Property tax [Member] Mississippi Power [Member]		Dec. 31, 2012 Recoverable Vacation Pay [Member]		Dec. 31, 2011 Recoverable Vacation Pay [Member]		Dec. 31, 2012 Recoverable Vacation Pay [Member] Gulf Power [Member]		Dec. 31, 2011 Recoverable Vacation Pay [Member] Gulf Power [Member]		Dec. 31, 2012 Recoverable Vacation Pay [Member] Alabama Power [Member]		Dec. 31, 2011 Recoverable Vacation Pay [Member] Alabama Power [Member]		Dec. 31, 2012 Recoverable Vacation Pay [Member] Georgia Power [Member]		Dec. 31, 2011 Recoverable Vacation Pay [Member] Georgia Power [Member]		Dec. 31, 2012 Recoverable Vacation Pay [Member] Mississippi Power [Member]		Dec. 31, 2011 Recoverable Vacation Pay [Member] Mississippi Power [Member]		Dec. 31, 2012 Retiree benefit plans [Member]		Dec. 31, 2011 Retiree benefit plans [Member]		Dec. 31, 2012 Retiree benefit plans [Member] Gulf Power [Member]		Dec. 31, 2011 Retiree benefit plans [Member] Gulf Power [Member]		Dec. 31, 2012 Retiree benefit plans [Member] Georgia Power [Member]		Dec. 31, 2011 Retiree benefit plans [Member] Georgia Power [Member]		Dec. 31, 2012 Retiree benefit plans [Member] Mississippi Power [Member]		Dec. 31, 2011 Retiree benefit plans [Member] Mississippi Power [Member]		Dec. 31, 2012 Storm damage [Member] Georgia Power [Member]	Dec. 31, 2010 Environmental remediation reserve [Member] Georgia Power [Member]	Dec. 31, 2012 Fuel Expense [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2011 Fuel Expense [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2010 Fuel Expense [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2012 Purchased Power [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2011 Purchased Power [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2010 Purchased Power [Member] Southern Power [Member] Gulf Power [Member]	Dec. 31, 2012 Other Postretirement Benefits [Member]	Dec. 31, 2011 Other Postretirement Benefits [Member]	Dec. 31, 2012 Other Postretirement Benefits [Member] Gulf Power [Member]	Dec. 31, 2011 Other Postretirement Benefits [Member] Gulf Power [Member]	Dec. 31, 2012 Other Postretirement Benefits [Member] Alabama Power [Member]	Dec. 31, 2011 Other Postretirement Benefits [Member] Alabama Power [Member]	Dec. 31, 2012 Other Postretirement Benefits [Member] Georgia Power [Member]	Dec. 31, 2011 Other Postretirement Benefits [Member] Georgia Power [Member]	Dec. 31, 2012 Other Postretirement Benefits [Member] Mississippi Power [Member]	Dec. 31, 2011 Other Postretirement Benefits [Member] Mississippi Power [Member]	Dec. 31, 2012 Electric Transmission [Member] Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2011 Electric Transmission [Member] Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2010 Electric Transmission [Member] Southern Company Services, Inc. [Member] Southern Power [Member]	Dec. 31, 2012 Plant Farley [Member] Alabama Power [Member]	Oct. 20, 2011 Plant Daniel Units 3 and 4 [Member] Mississippi Power [Member]	Dec. 31, 2012 Plant Daniel Units 3 and 4 [Member] Mississippi Power [Member]		Dec. 31, 2011 Plant Daniel Units 3 and 4 [Member] Mississippi Power [Member]		Dec. 31, 2012 Kemper IGCC [Member] Mississippi Power [Member]	Aug. 31, 2010 Kemper IGCC [Member] Mississippi Power [Member]	Jan. 02, 2008 Hurricane Katrina [Member] Mississippi Power [Member]	Dec. 31, 2012 Florida Power and Light [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2011 Florida Power and Light [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2010 Florida Power and Light [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2011 Progress Energy Carolina [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2010 Progress Energy Carolina [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2012 Progress Energy Florida [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2012 Georgia Power [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2011 Georgia Power [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 31, 2010 Georgia Power [Member] Sales Revenue, Goods, Net [Member] Customer Concentration Risk [Member] Southern Power [Member]	Dec. 19, 2011 Series B 6.25% Senior Notes due July 15, 2012 [Member] Southern Power [Member]	Dec. 31, 2012 Storm reserve [Member] Georgia Power [Member]	Dec. 31, 2010 Storm reserve [Member] Georgia Power [Member]	Dec. 31, 2012 Environmental remediation reserve [Member] Georgia Power [Member]	Dec. 31, 2010 Environmental remediation reserve [Member] Georgia Power [Member]	Dec. 31, 2012 Operating Lease PPA [Member] Southern Power [Member]	Dec. 31, 2011 Operating Lease PPA [Member] Southern Power [Member]	Dec. 31, 2010 Operating Lease PPA [Member] Southern Power [Member]	Dec. 31, 2012 Fuel Purchases [Member] Alabama Power [Member] Mississippi Power [Member]	Dec. 31, 2011 Fuel Purchases [Member] Alabama Power [Member] Mississippi Power [Member]	Dec. 31, 2010 Fuel Purchases [Member] Alabama Power [Member] Mississippi Power [Member]	Dec. 31, 2012 Fuel Purchases [Member] Mississippi Power [Member] Alabama Power [Member]	Dec. 31, 2011 Fuel Purchases [Member] Mississippi Power [Member] Alabama Power [Member]	Dec. 31, 2010 Fuel Purchases [Member] Mississippi Power [Member] Alabama Power [Member]	Dec. 31, 2012 Non-Fuel Expense [Member] Alabama Power [Member] Mississippi Power [Member]	Dec. 31, 2011 Non-Fuel Expense [Member] Alabama Power [Member] Mississippi Power [Member]	Dec. 31, 2010 Non-Fuel Expense [Member] Alabama Power [Member] Mississippi Power [Member]	Dec. 31, 2012 Non-Fuel Expense [Member] Mississippi Power [Member] Alabama Power [Member]	Dec. 31, 2011 Non-Fuel Expense [Member] Mississippi Power [Member] Alabama Power [Member]	Dec. 31, 2010 Non-Fuel Expense [Member] Mississippi Power [Member] Alabama Power [Member]	Dec. 31, 2012 Non-Fuel Expense [Member] Gulf Power [Member] Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2011 Non-Fuel Expense [Member] Gulf Power [Member] Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2010 Non-Fuel Expense [Member] Gulf Power [Member] Georgia Power [Member] Plant Scherer Unit 3 [Member]	Dec. 31, 2010 Storm Assistance [Member] Traditional Operating Companies [Member] Mississippi Power [Member]
Summary of Significant Accounting Policies [Line Items]
Original Maturities of Temporary Cash Investments	P90D																										P90D									P90D								P90D																			P90D																							P90D
Percentage Of Wholesale Customers To Operating Revenue																																																																																						22.00%
Period Of Contract Cancellation Notices Of Wholesale Customers																																																																																						10 years
Annual Rate Change Limit Under Performance Evaluation Plan, Percent																																																																																										1.99%	1.893%		1.936%
Variable Interest Entity, Consolidated, Carrying Amount, Assets																																																																																						$ 21,000,000
Jointly Owned Utility Plant, Proportionate Ownership Share						45.70%																												90.00%	10.00%	50.00%					25.00%			14.00%				86.00%																						75.00%			45.70%
Affiliate Transactions [Abstract]
Affiliate transaction amount																											159,900,000	175,900,000	230,800,000																																																																			6,900,000	6,700,000	8,900,000				147,000,000	171,000,000	199,000,000	125,400,000	112,700,000	105,200,000	95,900,000	97,400,000	98,800,000	340,000,000	347,000,000	371,000,000	540,000,000	550,000,000	552,000,000	212,700,000	185,500,000	125,100,000	218,000,000	215,000,000	218,000,000	574,000,000	537,000,000	473,000,000	21,100,000	23,400,000	25,000,000					21,200,000	23,300,000	25,000,000	15,000,000	21,000,000	107,700,000	87,900,000	89,600,000	19,000,000	20,600,000	30,500,000																																																		2,600,000	1,800,000	3,300,000	14,700,000	14,300,000	14,500,000											6,600,000	7,100,000	7,800,000																								76,200,000	75,600,000	68,100,000	28,100,000	20,900,000	16,100,000	28,000,000	21,000,000	16,000,000	11,700,000	12,200,000	11,200,000	12,000,000	12,000,000	11,000,000				2,000,000
Long-term Purchase Commitment, Minimum Power Required																																																																																																					292
Gulf Power agreement, commitment amount																																																																																																																																	38,000,000
Long-Term Purchase Commitment Amount In Year Two																																																																																																																																	22,000,000
Long-Term Purchase Commitment Amount In Year Three																																																																																																																																	29,000,000
Prepaid capacity expenses																																																																																																						15,000,000	16,000,000
Gulf Power agreement, percentage reimbursement of non-fuel expenses																																																																																																																																				25.00%
Deferred Capacity Expenses																																																															169,000,000	216,000,000	223,000,000																																				4,200,000																																											4,200,000
Gulf Power agreement, reimbursement of non-fuel expenses																																																																																																2,400,000	2,400,000	2,400,000																																2,400,000	2,400,000																																																																																																																							7,000,000	7,000,000	9,000,000
Revenue requirement obligations																																																																																																			136,700,000
Revenue Requirements Reimbursement																																																																																																			3,000,000
Strom restoration cost																																																																																																				1,400,000
Regulatory Assets and Liabilities, Table Footnotes
Life of related property over which deferred income tax liabilities are amortized				65 years																																				65 years							50 years																						65 years
Other cost of removal obligations related to Georgia Power	31,000,000																																																														31,000,000
Other cost of removal obligations, amortization period	1 year
Life of the new issue				50 years																																40 years											50 years																						50 years
Fuel hedging assets and liabilities, amortization period																																				5 years																											3 years																							2 years
Amortization of Regulatory Asset, Vacation Pay	1 year																																			1 year								1 year																			1 year																																																																																																												1 year
Recovery and amortization periods for regulatory assets (liabilities), approved by PSCs				10 years																																											5 years																																							10 years																																																																																																																																10 years
Recovery and amortization periods for regulatory assets (liabilities), average remaining service period				15 years																																				14 years							15 years																14 years																							14 years
Amortization Period of Regulatory Assets and Liabilities																																																																																						50 years																																																																	12 months																																																														10 years							4 years
Medicare Drug Subsidy Obligation Related To Subsidiary																																												21,000,000
Recovered and amortized as approved by the appropriate state PSCs				15 years																																1 year				14 years							15 years																10 years
Regulatory liability for state income tax credits amortization period	21 months																																																														21 months
Refueling cycles for Alabama Power and Georgia Power, minimum months	18 months																																											18 months																			18 months
Refueling cycles for Alabama Power and Georgia Power, maximum months	10 years																																																														24 months																						24 months
Net regulatory assets	4,322,000,000	3,865,000,000																																		171,985,000	117,626,000							703,000,000	716,000,000																		2,471,000,000	2,254,000,000																						147,469,000	75,795,000																																																																27,882,000	[1]	18,484,000	[1]	165,000,000	[2],[3]	160,000,000	[2],[3]	9,238,000	[2],[3]	8,973,000	[2],[3]	61,000,000	[2],[3]	59,000,000	[2],[3]	85,000,000	[3],[4]	82,000,000	[3],[4]	9,635,000	[2],[3]	9,128,000	[2],[3]	3,373,000,000	[2],[5]	2,959,000,000	[2],[5]	141,429,000	[2],[6]	116,091,000	[2],[6]	1,331,000,000	[4],[7]	1,197,000,000	[4],[7]	162,293,000	[2],[6]	130,678,000	[2],[6]																								12,386,000	[8]	3,945,000	[8]
Recovered and amortization periods as approved by appropriate state PSC																																								14 years
Recovery and Amortization Periods for Regulatory Assets Liabilities Approved by FERC																																																																																						5 years
Government Grants [Abstract]
Grants expected to be received from Department of Energy																																																																																																																																																																																																																										25,000,000	270,000,000
Grants received from Department of Energy																																																																																																																																																																																																																										245,300,000
Revenues [Abstract]
Projected fuel cost over or under recovery threshold, as a percentage of projected fuel revenue																																				10.00%			10.00%
Maximum revenue from a single customer or industry	10.00%																																			10.00%								10.00%																			10.00%																							10.00%																																																																																																																																							12.80%	14.70%	11.40%	8.30%	8.20%	5.90%	12.50%	14.00%	17.70%
Maximum percentage of uncollectible accounts	1.00%																																			1.00%								1.00%																			1.00%																							1.00%
Property, Plant and Equipment [Abstract]
Refueling cycles for Alabama Power and Georgia Power, minimum months	18 months																																											18 months																			18 months
Refueling cycles for Alabama Power and Georgia Power, maximum months	10 years																																																														24 months																						24 months
Amortization period of defer inspection costs for the combustion turbines																																																																							10 years
Amortization Period of Defer Costs of Certain Significant Inspection Costs for Combustion Turbines																																																																							10 years
Non-cash property additions recognized	524,000,000	929,000,000	427,000,000
Nuclear outage expense																																										31,000,000	38,000,000	31,000,000	38,000,000
Revenue bond obligations fair value																																																																																							346,000,000					346,000,000																																																																																																																									346,100,000
Operating lease, initial term																																																																																						10 years			10 years																																																																																																																												10 years
Cash payment to be made in conjunction with purchase of facility																																																																																												85,000,000																																																																																																																									84,800,000
Face value of debt obligations assumed																																																																																																																																																																																																																					270,000,000
Lesser obligation related to aggregate principal amount																											500,000			900,000	4,100,000																																2,300,000,000																													270,000,000
Fixed stated interest rate of debt obligation																																																															7.90%	7.40%																						9.967%						7.13%																																																																																																																									7.13%																	6.25%
Amount of Facility reflected in Southern Company and Mississippi Power financial statements		431,000,000
Income Tax Matters [Abstract]
Amortization of deferred investment tax credits	23,000,000	19,000,000	23,000,000																																	1,400,000	1,300,000	1,500,000						8,000,000	8,000,000	8,000,000																	13,000,000	9,000,000	13,000,000																					1,200,000	1,300,000	1,300,000
Credits amortized to income tax expense	2,600,000	900,000
Reduction in tax basis of assets																											50.00%
Depreciation and Amortization
Depreciation of cost of utility plant in service, composite straight-line rate																				3.20%	3.20%	3.30%														3.60%	3.50%	3.50%																						3.20%	3.30%	3.30%	2.90%	2.80%	3.00%																					3.50%	3.90%	3.40%
Accumulated depreciation for utility plant in service, total	21,964,000,000	21,154,000,000																		21,500,000,000	20,700,000,000		479,000,000	456,000,000			786,620,000	652,087,000								1,168,055,000	1,124,291,000							7,761,000,000	7,344,000,000																		10,431,000,000	10,296,000,000																						1,065,474,000	1,019,251,000
Regulatory liabilities amortized																																																															31,000,000
Amortization period of other cost of removal obligations																																																															3 years		3 years
Plant in service, estimated useful lives																									P3Y	P25Y						21	35
Plant acquisition adjustment	124,000,000	124,000,000																																		2,286,000	2,542,000				2,300,000			12,000,000	12,000,000																		28,000,000	28,000,000																						81,412,000	81,408,000																																																																																																																														81,400,000
Fair value adjustment at date of purchase																																																																																																																																																																																																																					76,051,000
Fair value adjustment at date of purchase, amortization term																																																																																																																																																																																																																					10 years
Amortization period of regulatory assets and liabilities																																																																																						50 years																																																																	12 months																																																														10 years							4 years
Impairment of Long-Lived Assets and Intangibles
Average term of PPAs																											20 years
Deferred Project Development Costs
Deferred project development costs																											11,200,000	9,900,000	9,600,000
Decommissioning
Estimated cost of decommissioning completion year					2068			2072																																																																2068			2072																																																																																																																																									2065
Minimum net worth requirement by a one or more persons to hold external trust funds	100,000,000																																											100,000,000																			100,000,000
Fair market value of fund's securities on loan under the Funds' managers' securities lending program	91,000,000	39,000,000																																																													91,000,000	39,000,000
Fair value of collateral received	93,000,000	42,000,000																																																													93,000,000	42,000,000
Decommissioning Fund Investments Net Of Foreign Currency																																												604,000,000	539,000,000																		698,000,000	666,000,000
Investment securities in the Funds	1,303,000,000	1,207,000,000							718,000,000	626,000,000	564,000,000	543,000,000	20,000,000	36,000,000																														605,000,000	540,000,000				438,000,000	382,000,000	156,000,000	146,000,000	10,000,000	11,000,000									698,000,000	667,000,000												850,000,000	1,800,000,000	1,800,000,000	280,000,000	244,000,000	408,000,000	397,000,000	10,000,000	25,000,000
Proceeds from sale of securities held in external trust funds	1,000,000,000	2,200,000,000	2,000,000,000																																									193,000,000	349,000,000	236,000,000
Increase (Decrease) in fair value of securities related to nuclear decommissioning	137,000,000	29,000,000	139,000,000												6,000,000	4,000,000	41,000,000	75,000,000	60,000,000																									70,000,000	6,000,000	65,000,000									51,000,000	31,000,000	4,000,000	41,000,000	50,000,000				67,000,000	23,000,000	74,000,000	25,000,000	9,000,000	25,000,000
Amount expensed for rate making purpose					2,000,000		3,000,000																																																																	2,000,000		3,000,000
Significant assumption of inflation rate used to determine the costs for rate making																																												4.50%																			2.40%
Significant assumption of trust earnings rate used to determine the costs for rate making																																												7.00%																			4.40%
Allowance for Funds Used During Construction and Interest Capitalized
Composite rate used to determine allowance for funds used during construction																																				6.72%		7.65%						9.40%	9.20%	9.40%																	6.80%	7.50%	8.00%																					7.04%	7.06%	7.33%
AFUDC capitalized																																																															75,000,000	134,000,000	201,000,000
AFUDC, net of income taxes	8.20%	9.10%	12.50%																																	5.36%	11.75%	7.39%						3.30%	3.90%	6.30%																	5.70%	10.40%	19.00%																					57.05%	31.60%	6.97%
Cash payments for interest totaled	803,000,000	832,000,000	789,000,000																								50,248,000	74,989,000	63,229,000							58,255,000	55,486,000	42,521,000						273,000,000	286,000,000	288,000,000																	337,000,000	346,000,000	339,000,000																					32,589,000	14,814,000	19,518,000
Net of amounts capitalized	83,000,000	78,000,000	86,000,000																								19,092,000	18,001,000	12,110,000							2,500,000	3,951,000	2,875,000						7,000,000	9,000,000	14,000,000																	21,000,000	37,000,000	54,000,000																					32,816,000	10,065,000	2,903,000
Reserves and Recoveries
Accrued reserves																																				32,000,000	30,500,000																																																									28,000,000	29,000,000
Additional accrued reserve to cover the cost of damages totaled for Alabama Power, Gulf Power, and Mississippi Power																																													31,000,000
Recovery Period For Natural Disaster Reserve Costs																																												24 months
Maximum total rate NDR charge per month, non-residential customer account																																												10
Maximum total rate NDR charge per month, residential customer account																																												5
Old Natural Disaster Reserve Authorized Limit																																												75,000,000
Costs recovered annually under rate plan																																																																	21,000,000																																																																																																																															1,000,000																																							18,000,000	21,000,000	3,000,000	1,000,000
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation																																				60,500,000																											19,000,000
PSC Approved Annual Property Damage Reserve Accrual																																				3,500,000																																																		3,200,000
PSC approved target level for property damage reserve																																							48,000,000	55,000,000
Threshold above which additional property damage reserves are authorized by PSC																																				3,500,000
Increase in accrued property damage costs																																				3,500,000	3,500,000	3,500,000
Cumulative damage costs limit under PSC order																																				10,000,000
Percentage of claimed costs to recover under surcharge																																				80.00%
PSC approved annual uninsured injuries and damages accrual																																				1,600,000				2,000,000
Threshold above which additional uninsured injuries and damages accruals are authorized by PSC																																				1,600,000
Reserve for losses and loss adjustment expenses																																				3,100,000	2,700,000																																																																																																														1,600,000	1,600,000	1,500,000	1,100,000
Net regulatory assets	4,322,000,000	3,865,000,000																																		171,985,000	117,626,000							703,000,000	716,000,000																		2,471,000,000	2,254,000,000																						147,469,000	75,795,000																																																																27,882,000	[1]	18,484,000	[1]	165,000,000	[2],[3]	160,000,000	[2],[3]	9,238,000	[2],[3]	8,973,000	[2],[3]	61,000,000	[2],[3]	59,000,000	[2],[3]	85,000,000	[3],[4]	82,000,000	[3],[4]	9,635,000	[2],[3]	9,128,000	[2],[3]	3,373,000,000	[2],[5]	2,959,000,000	[2],[5]	141,429,000	[2],[6]	116,091,000	[2],[6]	1,331,000,000	[4],[7]	1,197,000,000	[4],[7]	162,293,000	[2],[6]	130,678,000	[2],[6]																								12,386,000	[8]	3,945,000	[8]
Threshold above which actual damages are charged to the reserve																																																																																						50,000
Retail accrual per annual SRR rate																																																																																						3,500,000	3,800,000	3,100,000
Wholesale accrual per annual SRR rate																																																																																						300,000	300,000	300,000
Regulatory asset																																																																																																																																																																																															38,000,000										2,169,000	239,000
Other Regulatory Assets Current	163,000,000	239,000,000																																		30,576,000	35,849,000							24,000,000	44,000,000																		72,000,000	108,000,000																						55,302,000	69,201,000																																																																																																								18,000,000
Other Regulatory Assets Deferred	4,032,000,000	3,579,000,000																																		372,294,000	323,116,000							1,083,000,000	994,000,000																		1,798,000,000	1,604,000,000																						236,225,000	185,694,000																																																																																																								20,000,000								360,000,000	345,000,000			89,000,000	96,000,000	187,000,000	186,000,000	15,454,000	13,324,000
Leveraged Leases [Abstract]
Leveraged lease agreement term				45 years
Other Income and (Expense)
Repayments of Long-term Debt																																																																																																																																																																																																																																						575,000,000
Fixed stated interest rate of debt obligation																																																															7.90%	7.40%																						9.967%						7.13%																																																																																																																									7.13%																	6.25%
Loss recognized for early redemption of debt																																																																																																																																																																																																																																						19,800,000
Unamortized Nuclear Outage Expense																																												33,000,000
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities																																																																																						21,800,000
Annual Rate Change Under Performance Evaluation Plan, Amount																																																																																										15,800,000	17,400,000		16,100,000
After-Tax Adjustment To Income	17,000,000
Expected Potential Impairment Loss on Abandonment of Project	90,000,000
Long-term Purchase Commitment, Period Over Which Costs Are Expected to Be Recovered																																																																																																																																	2023
Environmental Regulatory Assets																																																																																																																																																	$ 3,000,000	$ 11,000,000

[1] Recovered through the ad valorem tax adjustment clause over a 12-month period beginning in April of the following year.

[2] Not earning a return as offset in rate base by a corresponding asset or liability.

[3] Recorded as earned by employees and recovered as paid, generally within one year. This includes both vacation and banked holiday pay.

[4] Not earning a return as offset in rate base by a corresponding asset or liability

[5] Recovered and amortized over the average remaining service period which may range up to 15 years. See Note 2 for additional information.

[6] Recovered and amortized over the average remaining service period which may range up to 14 years. See Note 2 for additional information.

[7] Recovered and amortized over the average remaining service period which may range up to 14 years. See Note 2 under "Pension Plans" and "Other Postretirement Benefits" for additional information.

[8] Recovered and amortized over a 10-year period ending October 2021, as approved by the Mississippi PSC for the difference between the revenue requirement under the purchase option and the revenue requirement assuming operating lease accounting treatment for the extended term.