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REGULATORY MATTERS - MPC Environmental Compliance Overview Plan (Details) - Mississippi Power - USD ($) $ in Millions		1 Months Ended				12 Months Ended
	Apr. 05, 2022	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	May 31, 2021	Dec. 31, 2020
Public Utilities, General Disclosures [Line Items]
Public utilities, approved rate increase (decrease), amount		$ 18.0	$ 9.0	$ 16.0	$ 28.0	$ (16.7)
Environmental Compliance Overview Plan
Public Utilities, General Disclosures [Line Items]
Public utilities, approved rate increase (decrease), amount	$ (1.0)			$ (9.0)

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Amount of public utility's approved rate increase (decrease) by regulatory agency.

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