Stock-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Stock-Based Compensation Activity
Income tax benefit	$ 0.8	$ 1.0
Maximum payout range	29.00%oge_MaximumPayoutRange
Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	2.4	3.7
Total Shareholder Return [Member]
Stock-Based Compensation Activity
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	264,454
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 31.02
Equity Instruments Other than Options, Converted in Period	336,147
Performance Units Related to Earnings Per Share [Member]
Stock-Based Compensation Activity
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	88,156
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 33.99
Equity Instruments Other than Options, Converted in Period	111,950
Restricted Stock [Member]
Stock-Based Compensation Activity
Compensation expense	0	0.1
Stock Compensation Plan [Member]
Stock-Based Compensation Activity
Compensation expense	2.4	3.8
Amount paid by unconsolidated affiliates	0.3	1.2
Net compensation expense	2.1	2.6
Common Stock
Stock-Based Compensation Activity
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	80,781
Restricted Stock [Member]
Stock-Based Compensation Activity
Shares Paid for Tax Withholding for Share Based Compensation	979
Total Shareholder Return [Member] \| Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	1.9	2.0
Performance Units Related to Earnings Per Share [Member] \| Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	$ 0.5	$ 1.7

Allocated Share-Based Compensation Expense, Net of Unconsolidated Affiliates

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Amount Attributable to Unconsolidated Affiliates

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Equity Instruments Other than Options, Converted in Period

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- Definition

Maximum payout range

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

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-Topic 718

-SubTopic 10

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-Section 50

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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

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- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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- Definition

Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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-Name Accounting Standards Codification

-Topic 505

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-Number 210

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