FINANCING - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Alabama Power \| Trust Preferred Securities
Debt Disclosure [Line Items]
Long-term debt	$ 206	$ 206
Mississippi Power \| Secured Debt
Debt Disclosure [Line Items]
Long-term debt	270	270
Mississippi Business Finance Corporation Taxable Revenue Bonds Series 1999A Due 2021 \| Mississippi Power \| Corporate bonds
Debt Disclosure [Line Items]
Long-term debt	$ 270	$ 270
Fixed stated interest rate of debt obligation	7.13%	7.13%
Long-term debt, fair value	$ 346
Unamortized premium	76
Tax-exempt Revenue Bonds \| Mississippi Power \| Secured Debt
Debt Disclosure [Line Items]
Long-term debt	$ 50	$ 50

[Line Items] for Debt Disclosure [Table]

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt premium.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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