Contingencies and Regulatory Matters - Narrative (Details)												1 Months Ended				3 Months Ended		6 Months Ended			10 Months Ended	12 Months Ended								54 Months Ended	84 Months Ended
	Jun. 30, 2016 USD ($) mi	Jun. 09, 2016 USD ($)	Jun. 03, 2016	May 01, 2016 USD ($)	Mar. 31, 2016	Dec. 03, 2015 USD ($)	Jul. 07, 2015 USD ($)	Jun. 30, 2015 USD ($)	Apr. 15, 2015 USD ($)	Jan. 01, 2014 USD ($)	Mar. 19, 2013	Apr. 30, 2016 MW	Dec. 31, 2015 USD ($)	Feb. 28, 2013 USD ($)	Jan. 31, 2013 USD ($)	Jun. 30, 2016 USD ($) mi	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) clause mi MW	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Oct. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2010	Dec. 31, 2009 USD ($)	Dec. 31, 2008 USD ($)	Jun. 30, 2016 USD ($) mi	Dec. 31, 2022	Jun. 30, 2019 USD ($)	Jul. 28, 2016 MW	May 17, 2016 USD ($)	May 03, 2016 USD ($)	Apr. 01, 2016 USD ($)	Mar. 09, 2016 USD ($)	Feb. 01, 2016 USD ($)	Jan. 05, 2016 USD ($)	Jul. 10, 2015 USD ($)
Loss Contingencies [Line Items]
Maximum Borrowing Capacity	$ 6,500,000,000															$ 6,500,000,000		$ 6,500,000,000												$ 6,500,000,000
Construction work in progress	9,451,000,000												$ 9,082,000,000			9,451,000,000		9,451,000,000	$ 9,082,000,000				$ 9,082,000,000							9,451,000,000
Projected Balance Of Regulatory Assets	350,000,000												402,000,000			350,000,000		350,000,000	402,000,000				402,000,000							350,000,000
Kemper IGCC [Member]
Loss Contingencies [Line Items]
Pre-Tax Charge To Income																81,000,000	$ 23,000,000	134,000,000		$ 32,000,000
After Tax Charge To Income																50,000,000	$ 14,000,000	83,000,000		$ 20,000,000
Georgia Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation	23,000,000															23,000,000		23,000,000												23,000,000
Rate ECR Increase Decrease																																		15.00%
Approved Increase (Decrease) in Annual Billing Based on Fuel Cost Recovery Rate																																		$ (313,000,000)
Additional Construction Capital Costs								$ 3,100,000,000											160,000,000
Percentage of Proportionate Share Owed in Consortium Agreement																													45.70%
Maximum Borrowing Capacity	1,750,000,000															1,750,000,000		$ 1,750,000,000												1,750,000,000
Increase (Decrease) In Projected Certified Construction Capital Costs																		5.00%
Estimated In-service Capital Cost																												$ 4,400,000,000
Amendment To Estimated In-service Capital Cost														$ 4,800,000,000
Delay Of Estimated In-service Date									18 months
Construction work in progress	4,655,000,000												4,775,000,000			4,655,000,000		$ 4,655,000,000	4,775,000,000				4,775,000,000							4,655,000,000
Projected Balance Of Regulatory Assets	123,000,000												123,000,000			123,000,000		123,000,000	123,000,000				123,000,000							123,000,000
Georgia Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Additional Construction Capital Costs																													$ 114,000,000
Georgia Power [Member] | Other Current Liabilities [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Balance	164,000,000															164,000,000		164,000,000												164,000,000
Georgia Power [Member] | Other deferred credits and liabilities [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Balance													116,000,000						116,000,000				116,000,000
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member]
Loss Contingencies [Line Items]
Additional Construction Capital Costs																		141,000,000
Maximum Borrowing Capacity																																					$ 920,000,000
Estimated In-service Capital Cost									$ 5,000,000,000
Monthly Operational Readiness Costs									$ 10,000,000
Construction Financing Costs	1,100,000,000
Construction work in progress	3,700,000,000															3,700,000,000		3,700,000,000												3,700,000,000
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Project Settlement Cost To Be Capitalized													350,000,000						350,000,000				350,000,000
Project Settlement Cost To Be Capitalized, Amount Paid To Date	250,000,000															250,000,000		250,000,000												250,000,000
Gulf Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation	46,000,000															46,000,000		46,000,000												46,000,000
Maximum Borrowing Capacity	280,000,000															280,000,000		280,000,000												280,000,000
Construction work in progress	68,000,000												48,000,000			68,000,000		68,000,000	48,000,000				48,000,000							68,000,000
Reduction In Depreciation Expense																									$ 62,500,000
Reduction In Depreciation Expense Year One																		$ 6,400,000					20,100,000	$ 8,400,000
Number Of Regulatory Clauses | clause																		4
Projected Balance Of Regulatory Assets	65,000,000												90,000,000			65,000,000		$ 65,000,000	90,000,000				90,000,000							65,000,000
Mississippi Power [Member]
Loss Contingencies [Line Items]
Increase in Base Rate Under Cost Based Electric Tariff Due to Settlement				$ 7,000,000
Over Recovered Fuel Cost	76,000,000												71,000,000			76,000,000		76,000,000	71,000,000				71,000,000							76,000,000
Approved Increase (Decrease) in Annual Billing Based on Fuel Cost Recovery Rate																																						$ (36,000,000)	$ (120,000,000)
Maximum Borrowing Capacity	175,000,000															175,000,000		175,000,000												175,000,000
Construction work in progress	2,429,000,000												2,254,000,000			2,429,000,000		$ 2,429,000,000	2,254,000,000				2,254,000,000							2,429,000,000
PSC Retail Rate Increase (Decrease)																																			$ (2,000,000)
Annual PEP Filing Rate Increase Amount																																				$ 5,000,000
Plant Capacity Under Coal Gasification Combined Cycle Technology (in MWs) | MW																		582
Costs associated with CCP12 grant funds																										$ 245,000,000
Increase Retail Rates In Year One											15.00%
Increase Retail Rates In Year Two										3.00%
Settlement Agreement Collection Amount To Mitigate Rate Impact Year Two										$ 156,000,000
Retail Rate Recovery							$ 342,000,000
Carrying Costs Associated With Retail Rate Recovery							$ 29,000,000
Projected Balance Of Regulatory Assets	97,000,000												95,000,000			97,000,000		$ 97,000,000	95,000,000				95,000,000							97,000,000
Regulatory Liabilities	5,000,000															5,000,000		5,000,000												5,000,000
Mississippi Power [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Costs Due To Extension Of In-service Date																		25,000,000
Mississippi Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Costs Due To Extension Of In-service Date																		35,000,000
Mississippi Power [Member] | Construction in Progress [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	2,550,000,000															2,550,000,000		2,550,000,000												2,550,000,000
Mississippi Power [Member] | MRA Revenue [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Cost	$ 23,000,000												24,000,000			$ 23,000,000		$ 23,000,000	24,000,000				24,000,000							$ 23,000,000
Mississippi Power [Member] | Electricity Generation Plant, Non-Nuclear [Member]
Loss Contingencies [Line Items]
Estimated Cost															$ 2,400,000,000											2,400,000,000
Alternate Financing																									$ 1,000,000,000
Mississippi Power [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Period of Amortization of Regulatory Assets					36 months
Co Two Pipeline Infrastructure (in miles) | mi	61															61		61												61
Estimated Cost																		$ 5,150,000,000								$ 2,880,000,000
Costs associated with CCP12 grant funds																		$ (140,000,000)
Period of Extension for In-service Date																		1 month
Pre-Tax Charge To Income																$ 81,000,000		$ 134,000,000												$ 2,550,000,000
After Tax Charge To Income																$ 50,000,000		83,000,000												$ 1,570,000,000
Monthly Charge Of Allowance For Equity Funds Used During Construction																		14,000,000
Monthly Cost Regulatory Assets Deferred																		$ 3,000,000
Purchase of Interest	100.00%					15.00%										100.00%		100.00%												100.00%
Maximum Cap Construction Cost																		$ 6,320,000,000
Regulatory Assets	$ 114,000,000															$ 114,000,000		114,000,000												$ 114,000,000
Projected Balance Of Regulatory Assets	101,000,000															101,000,000		101,000,000												101,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Estimate [Member]
Loss Contingencies [Line Items]
Estimated Cost																		5,430,000,000
Costs associated with CCP12 grant funds																		(140,000,000)
Maximum Cap Construction Cost																		$ 6,680,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | In-Service Asset Proposal [Member]
Loss Contingencies [Line Items]
PSC Retail Rate Increase (Decrease)						$ 126,000,000																																		$ 159,000,000
Public Utilities, Approved Equity Capital Structure, Percentage						49.733%
Public Utilities, Approved Return on Equity, Percentage						9.225%
Customer Refund													11,000,000
Period to File Subsequent Rate Request						18 months
Mississippi Power [Member] | Kemper IGCC [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value		$ 100,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Amortization Period of Regulatory Assets and Liabilities																		2 years
Mississippi Power [Member] | Kemper IGCC [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Estimated Cost																		$ 2,880,000,000
Amortization Period of Regulatory Assets and Liabilities																		10 years
Mississippi Power [Member] | Kemper IGCC [Member] | Property, Plant and Equipment [Member]
Loss Contingencies [Line Items]
Estimated Cost																		$ 3,590,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other Property And Investments [Member]
Loss Contingencies [Line Items]
Estimated Cost																		6,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Fossil Fuel Stock [Member]
Loss Contingencies [Line Items]
Estimated Cost																		81,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Materials And Supplies [Member]
Loss Contingencies [Line Items]
Estimated Cost																		46,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other regulatory assets deferred [Member]
Loss Contingencies [Line Items]
Estimated Cost																		35,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other regulatory assets, deferred [Member]
Loss Contingencies [Line Items]
Estimated Cost																		180,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other current assets [Member]
Loss Contingencies [Line Items]
Estimated Cost																		1,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other deferred charges and assets [Member]
Loss Contingencies [Line Items]
Estimated Cost																		11,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Assets [Member]
Loss Contingencies [Line Items]
Regulatory Assets	35,000,000															35,000,000		35,000,000												35,000,000
Mississippi Power [Member] | Mine [Member]
Loss Contingencies [Line Items]
Term of Management Fee Contract																											40 years
Alabama Power [Member]
Loss Contingencies [Line Items]
Maximum Borrowing Capacity	1,335,000,000															1,335,000,000		1,335,000,000												1,335,000,000
Construction work in progress	423,000,000												801,000,000			423,000,000		423,000,000	801,000,000				801,000,000							423,000,000
Projected Balance Of Regulatory Assets	$ 87,000,000												$ 115,000,000			$ 87,000,000		$ 87,000,000	$ 115,000,000				$ 115,000,000							$ 87,000,000
Alabama Power [Member] | Plant Greene County Units 1 And 2 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units | MW												300
Scenario, Forecast [Member] | Georgia Power [Member]
Loss Contingencies [Line Items]
Cost Recovery, New Nuclear																																$ 99,000,000
Additional Construction Capital Costs																						$ 5,440,000,000
Scenario, Forecast [Member] | Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member]
Loss Contingencies [Line Items]
Construction Financing Costs																						$ 2,400,000,000
Scenario, Forecast [Member] | Mississippi Power [Member]
Loss Contingencies [Line Items]
AFUDC Cost																					$ 8,000,000
Scenario, Forecast [Member] | Georgia Power And Atlanta Gas Light Company [Member]
Loss Contingencies [Line Items]
Percentage Basis, Net Merger Savings																															40.00%
Customers [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Percentage Basis, Net Merger Savings																															60.00%
Subsequent Event [Member] | Georgia Power [Member]
Loss Contingencies [Line Items]
Capacity of Renewable Resources Approved For Procurement | MW																																	1,200
Capacity of Renewable Resources Approved For Self-build | MW																																	200
Subsequent Event [Member] | Georgia Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Capacity of Renewable Resources Considered For Renewable Commercial and Industrial Program | MW																																	200
Subsequent Event [Member] | Georgia Power [Member] | Plant Mitchell Units 3, 4A, and 4B [Member]
Loss Contingencies [Line Items]
Capacity Of Units Approved For Decertification Of Units | MW																																	217
Subsequent Event [Member] | Georgia Power [Member] | Plant Kraft Unit 1 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Approved For Decertification Of Units | MW																																	17
Intercession City Combustion Turbine [Member] | Subsequent Event [Member] | Georgia Power [Member]
Loss Contingencies [Line Items]
Capacity Of Units Approved For Decertification Of Units | MW																																	143
Jointly Owned Utility Plant, Proportionate Ownership Share																																	33.00%
Denbury Onshore, Contractor [Member] | Mississippi Power [Member] | Electricity Generation Plant, Non-Nuclear [Member]
Loss Contingencies [Line Items]
Long-term Contract For Purchase of Carbon Dioxide, Term			16 years
Treetop Midstream Services, LLC, Contractor [Member] | Mississippi Power [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Long Term Contract For Purchase Of Percentage of Carbon Dioxide Captured from Plant	30.00%															30.00%		30.00%												30.00%
Denbury Onshore, Contractor [Member] | Mississippi Power [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Long Term Contract For Purchase Of Percentage of Carbon Dioxide Captured from Plant	70.00%		100.00%													70.00%		70.00%												70.00%