Rate Matters and Regulation (Details) (USD $) In Millions, unless otherwise specified					12 Months Ended					3 Months Ended
	Sep. 30, 2011 OG&E Wholesale Agreement [Member]	Sep. 30, 2011 OG&E 2010 Arkansas Rate Case Filing [Member]	Jun. 17, 2011 OG&E 2010 Arkansas Rate Case Filing [Member]	Sep. 28, 2010 OG&E 2010 Arkansas Rate Case Filing [Member]	Dec. 31, 2011 OG&E SPP Cost Tracker [Member]	Sep. 30, 2011 Review of OG&E's Fuel Adjustment Clause for Calendar Year 2009 [Member]	Mar. 11, 2011 Review of OG&E's Fuel Adjustment Clause for Calendar Year 2009 [Member]	Sep. 30, 2011 OG&E Smart Grid Project [Member]	Sep. 30, 2011 OG&E FERC Transmission Rate Incentive Filing [Member]	Sep. 30, 2011 OG&E Demand and Energy Efficiency Program Filing [Member]	Sep. 30, 2011 OG&E 2011 Oklahoma Rate Case Filing [Member]
Regulatory Matters [Line Items]
Customer Contract Contribution to OG&E's Gross Margin for 2010	$ 17.4
Customer Contract Percentage Contribution to OG&E's Gross Margin for 2010	1.50%
Amount of Regulatory Costs Approved										7.0
Requested Rate Dollar Increase				17.7							73.3
Recovery Of And Return On Significant Electric System Expansions and Upgrades and Increased Operating Costs			8.8
Recovery of Actual Costs of Third Party Transmission Charges and SPP Administration Fees			1.0
Maximum Deferral of Certain Expenses Associated with Customer Educational Program not to Exceed Two Years			0.3
Maximum Length of Deferred Expenses to be Expended		2 years
Anticipated Recovery of Incremental Revenues					1.8
Percent of Requested Recovery of Incurred Construction Costs									100.00%
Expected Increase in Residential Electric Bill										1.47
Customer Refund Requested Related to Regulatory Matters							15.5
Refund to Customers 2009 Fuel Clause Review						8.4
Amount Refunded to Customers 2009 Fuel Clause Review						4.9
Expected Capital Expenditures Net of Governmental Funds Received								14
Requested Rate Percentage Increase											4.30%
Requested Return on Equity											11.00%
Common Equity Percentage in Determining Return on Equity											53.00%
Incremental Change in Return on Equity											0.10%
Effect of Return on Equity Change on Requested Rate Increase											3.0
New Capital Investments											$ 500
Long-term Purchase Commitment, Time Period										3 years