Long-Term Debt (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Total long-term debt	$ 2,755.3us-gaap_LongTermDebt	$ 2,400.1us-gaap_LongTermDebt
Percent of Principal Amount Subject to Optional Tender	100.00%
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	0.2
Long-term Debt, Maturities, Repayments of Principal in Year Two	110.2
Long-term Debt, Maturities, Repayments of Principal in Year Three	225.1
Long-term Debt, Maturities, Repayments of Principal in Year Four	250.1
Long-term Debt, Maturities, Repayments of Principal in Year Five	250.1
Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Date Due	Jan. 01, 2025
Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Date Due	Jan. 01, 2025
Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Date Due	Jun. 01, 2027
Redeemable during the next 12 months
Debt Instrument [Line Items]
Total long-term debt	135.4
Redeemable during the next 12 months \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Series Minimum	0.07%
Series Maximum	0.20%
Redeemable during the next 12 months \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Series Minimum	0.07%
Series Maximum	0.18%
Redeemable during the next 12 months \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Series Minimum	0.04%
Series Maximum	0.15%
OG&E [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Long term debt, gross	47.0	47.0
OG&E [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Long term debt, gross	32.4	32.4
OG&E [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Long term debt, gross	56.0	56.0
Senior Notes [Member] \| OG&E [Member] \| Series due March 15, 2044 [Member]
Debt Instrument [Line Items]
Long term debt, gross	250.0	0
Debt Instrument, Interest Rate, Stated Percentage	4.55%
Date Due	Mar. 15, 2044
Senior Notes [Member] \| OG&E [Member] \| Series due December 15, 2044 [Member]
Debt Instrument [Line Items]
Long term debt, gross	250.0	0
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Date Due	Dec. 15, 2044
Senior Notes [Member] \| OG&E [Member] \| Series Due August 1, 2034 [Member]
Debt Instrument [Line Items]
Long term debt, gross	0	140.0
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Date Due	Aug. 01, 2034
Debt Instrument, Repurchased Face Amount	140.0
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	103.25%
Redemption Premium	4.6
Senior Notes [Member] \| OGE Energy [Member] \| Series Due November 24, 2017 [Member]
Debt Instrument [Line Items]
Long term debt, gross	$ 100.0	$ 0
Date Due	Nov. 24, 2017

Percent of Principal Amount Subject to Optional Tender

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Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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

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Maximum 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 CCYY-MM-DD format.

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Percentage of principal amount of debt redeemed.

+ References

No definition available.

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Face (par) amount of the original debt instrument that was repurchased.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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The excess of the (1) fair value of consideration transferred to the holders of a security in excess of (2) the carrying amount of the security reported on the registrant's balance sheet, which will be deducted from net earnings to derive net earnings available to common shareholders. This amount is generally an adjustment considered in the computation of earnings per share.

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No definition available.

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