REGULATORY MATTERS - GPC Rate Plans, Integrated Resource Plan and COVID-19 Costs (Details) $ in Millions								4 Months Ended	12 Months Ended
	Jan. 01, 2024 MW	Jan. 31, 2022 agreement MW	Jan. 01, 2022 USD ($)	Nov. 18, 2021 USD ($)	Nov. 02, 2021 USD ($)	Jun. 15, 2021 USD ($)	Jan. 01, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2035 MW	Dec. 31, 2030 MW	Dec. 31, 2029 MW	Dec. 31, 2028 MW	Dec. 31, 2026 MW	Dec. 31, 2025 MW	Dec. 31, 2024 MW	Dec. 31, 2021 USD ($) MW	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2013
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																$ 4,711.0	$ 5,493.0
Customer Refunds
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																(189.0)	$ (56.0)
Georgia Power
Public Utilities, General Disclosures [Line Items]
Approved rate increase							$ 90.0
Approved rate decrease							$ 10.0
Retail rate of return on common equity																		10.50%		10.95%
Portion of actual earnings above approved ROE band applied to reduce regulatory assets																		40.00%
Portion of actual earnings above approved ROE band retained by subsidiary company																		20.00%
Portion of actual earnings above approved ROE band refunded to customers																	50.00%	40.00%		66.67%
Customer refund liability in absence of base rate case																$ 5.0		$ 110.0
Portion of actual earnings above approved ROE band refunded to customers, value																	$ 50.0	$ 60.0
Portion of actual earnings above approved ROE band retained by Georgia Power																				33.33%
Portion of actual earnings above approved ROE band refunded to customers, used to reduce regulatory assets																	50.00%	50.00%
Portion of actual earning above approved ROE band refunded to customers, used to reduce regulatory assets, value																	$ 60.0		$ 50.0
Public utilities, approved rate increase (decrease), amount				$ 252.0				$ (44.0)
Requested additional generating capacity (in MW) | MW																970
Approved additional generating capacity (in MW) | MW																970
Incremental COVID-19 costs deferred																$ 21.0	38.0
Incremental COVID-19 costs deferred, bad debt costs																	23.0
Incremental COVID-19 costs deferred, other																	15.0
Net regulatory assets																3,928.0	4,252.0
Georgia Power | Plant Vogtle Unit 3
Public Utilities, General Disclosures [Line Items]
Public utilities, approved rate increase (decrease), amount					$ 2,100.0
Requested rate increase (decrease), amount					3,600.0
Approved depreciation expense deferred, annual amount					$ 38.0
Requested rate increase, annual amount						$ 302.0
Georgia Power | Plant Wansley Units 1 and 2
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																610.0
Georgia Power | Plant Bowen Units 1 and 2
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																937.0
Georgia Power | Plant Scherer Unit 3
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																622.0
Georgia Power | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW									3,700
Requested number of power purchase agreements to be certified | agreement		6
Requested number of affiliate power purchase agreements to be certified | agreement		5
Georgia Power | Subsequent Event | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW	1,567									1,000	2,300	228	265	380	88
Georgia Power | Subsequent Event | Plant Vogtle Unit 3
Public Utilities, General Disclosures [Line Items]
Decrease in tariff			$ 78.0
Georgia Power | Subsequent Event | Plant Wansley Units 1 and 2
Public Utilities, General Disclosures [Line Items]
Capacity of units included in request for decertification of units | MW		926
Request for decertification of units, percentage of ownership		53.50%
Georgia Power | Subsequent Event | Plant Bowen Units 1 and 2
Public Utilities, General Disclosures [Line Items]
Capacity of units included in request for decertification of units | MW		1,400
Georgia Power | Subsequent Event | Plant Scherer Unit 3
Public Utilities, General Disclosures [Line Items]
Capacity of units included in request for decertification of units | MW		614
Request for decertification of units, percentage of ownership		75.00%
Georgia Power | Subsequent Event | Plant Gaston Units 1 through 4
Public Utilities, General Disclosures [Line Items]
Capacity of units included in request for decertification of units | MW		500
Request for decertification of units, percentage of ownership		50.00%
Georgia Power | Subsequent Event | Plant Bowen Units 3 and 4
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW		1,760
Georgia Power | Subsequent Event | Plant Scherer Units 1 and 2
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW		137
Percent ownership		8.40%
Georgia Power | Subsequent Event | Plant Sinclair
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW		45
Georgia Power | Subsequent Event | Plant North Highlands
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW		30
Georgia Power | Subsequent Event | Plant Burton
Public Utilities, General Disclosures [Line Items]
Requested additional generating capacity (in MW) | MW		6
Georgia Power | Customer Refunds
Public Utilities, General Disclosures [Line Items]
Portion of actual earnings above approved ROE band refunded to customers, value																5.0		$ 110.0
Net regulatory assets																(8.0)	(6.0)
Remaining Net Book Value of Retired Assets
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																1,050.0	1,183.0
Remaining Net Book Value of Retired Assets | Georgia Power
Public Utilities, General Disclosures [Line Items]
Net regulatory assets																$ 455.0	$ 527.0
Maximum | Georgia Power
Public Utilities, General Disclosures [Line Items]
Retail rate of return on common equity																		12.00%		12.00%
Maximum | Remaining Net Book Value of Retired Assets | Georgia Power
Public Utilities, General Disclosures [Line Items]
Regulatory asset amortization period																		3 years
Minimum | Georgia Power
Public Utilities, General Disclosures [Line Items]
Retail rate of return on common equity																		9.50%		10.00%