Long-Term Debt (Details) $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($)
Debt Instrument [Line Items]
Percent of Principal Amount Subject to Optional Tender	100.00%
Debt Instrument, Face Amount	$ 1,000.0
Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jan. 01, 2025
Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jan. 01, 2025
Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jun. 01, 2027
Redeemable during the next 12 months
Debt Instrument [Line Items]
Long-term Debt	$ 135.4
OG&E [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Long term debt	47.0
OG&E [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Long term debt	32.4
OG&E [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Long term debt	$ 56.0
Minimum [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.11%
Minimum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.11%
Minimum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.11%
Maximum [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.27%
Maximum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.33%
Maximum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.27%
Senior Notes \| OG&E [Member] \| Series Due May 26, 2023
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.553%
Debt Instrument, Maturity Date	May 26, 2023
Debt Instrument, Face Amount	$ 500.0
Senior Notes \| OGE Energy [Member] \| Series Due May 26, 2023
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.703%
Debt Instrument, Maturity Date	May 26, 2023
Debt Instrument, Face Amount	$ 500.0

Percent of Principal Amount Subject to Optional Tender

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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Face (par) amount of debt instrument at time of issuance.

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

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Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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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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