Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
NON-CASH INVESTING AND FINANCING ACTIVITIES
Installment payments for Tinker electric distribution system	$ 0	$ 0	$ 10.6
Power plant long-term service agreement	0ogec_PowerPlantLongTermServiceAgreement	9.7ogec_PowerPlantLongTermServiceAgreement	0ogec_PowerPlantLongTermServiceAgreement
SUPPLEMENTAL CASH FLOW INFORMATION
Interest (net of interest capitalized)	143.6us-gaap_InterestPaidNet	127.5us-gaap_InterestPaidNet	122.1us-gaap_InterestPaidNet
Income taxes (net of income tax refunds)	0.2us-gaap_IncomeTaxesPaidNet	(5.5)us-gaap_IncomeTaxesPaidNet	(1.2)us-gaap_IncomeTaxesPaidNet
Interest costs capitalized	$ 2.4us-gaap_InterestCostsCapitalized	$ 3.4us-gaap_InterestCostsCapitalized	$ 3.5us-gaap_InterestCostsCapitalized

Installment payments for Tinker electric distribution system

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- Definition

Power Plant Long-Term Service Agreement

+ References

No definition available.

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

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- Definition

Amount of interest capitalized during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Allowance for Funds Used during Construction

-URI http://asc.fasb.org/extlink&oid=6504829

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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The amount of cash paid for interest during the period net of cash paid for interest that is capitalized.

+ References

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