REGULATORY MATTERS - APC Certificate of Convenience and Necessity and RGC (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 MW	Dec. 31, 2023 USD ($)	Jun. 14, 2023 MW	Jun. 13, 2023 MW	Apr. 04, 2023 claim MW	Dec. 31, 2022 USD ($)
Schedule of Regulatory Assets and Liabilities [Line Items]
Plant in service, net of depreciation | $		$ 90,703				$ 82,232
Approved solar PPAs | claim					2
Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Plant in service, net of depreciation | $		$ 24,298				$ 23,002
Renewable generation certificate, authorized generating capacity (in MWs)					500
Additional generating capacity (in MWs)					160
Renewable generation certificate, generating capacity (in MWs)					490
Additional renewable capacity (in MWs)			2,400
Size of allowable projects (in MWs)			200	80
Approval limit (in MWs)			400	160
Plant Barry Unit 8 | Alabama Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Approximate nameplate capacity (in MWs)	720