Retirement Plans and Postretirement Benefit Plans (Details) (USD $) In Millions	3 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended			9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Pension Plans, Defined Benefit [Member]	Sep. 30, 2010 Pension Plans, Defined Benefit [Member]	Sep. 30, 2011 Pension Plans, Defined Benefit [Member]	Sep. 30, 2010 Pension Plans, Defined Benefit [Member]	Sep. 30, 2011 Pension Plan [Member]		Sep. 30, 2010 Pension Plan [Member]		Sep. 30, 2011 Pension Plan [Member]		Sep. 30, 2010 Pension Plan [Member]		Sep. 30, 2011 Restoration of Retirement Income Plan [Member]		Sep. 30, 2010 Restoration of Retirement Income Plan [Member]		Sep. 30, 2011 Restoration of Retirement Income Plan [Member]		Sep. 30, 2010 Restoration of Retirement Income Plan [Member]		Sep. 30, 2011 Postretirement Benefit Plans [Member]		Sep. 30, 2010 Postretirement Benefit Plans [Member]	Sep. 30, 2011 Postretirement Benefit Plans [Member]		Sep. 30, 2010 Postretirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost							$ 4.4	[1]	$ 4.1	[1]	$ 13.2	[2]	$ 12.5	[2]	$ 0.3	[1]	$ 0.3	[1]	$ 0.8	[2]	$ 0.7	[2]	$ 0.8		$ 1.1	$ 2.6		$ 3.2
Interest cost							8.4	[1]	8.0	[1]	25.0	[2]	23.9	[2]	0.1	[1]	0.2	[1]	0.4	[2]	0.4	[2]	3.2		4.2	9.4		12.7
Expected return on plan assets							(11.4)	[1]	(10.6)	[1]	(34.1)	[2]	(31.8)	[2]									(1.2)		(1.7)	(3.8)		(5.2)
Amortization of transition obligation																							0.7		0.7	2.1		2.1
Amortization of net gains (losses)							4.8	[1]	5.3	[1]	14.4	[2]	15.9	[2]	0.1	[1]	0	[1]	0.3	[2]	0.2	[2]	4.6		3.0	13.7		9.1
Amortization of unrecognized prior service cost							0.6	[1]	0.6	[1]	1.8	[2]	1.8	[2]	0.1	[1]	0.1	[1]	0.5	[2]	0.5	[2]	(4.2)		0	(12.4)		0
Net Periodic Benefit Cost			7.4	8.0	22.3	24.1	6.8	[1]	7.4	[1]	20.3	[2]	22.3	[2]	0.6	[1]	0.6	[1]	2.0	[2]	1.8	[2]	3.9	[3]	7.3	11.6	[3]	21.9
Additional Pension Expense to Meet State Requirements			2.7	2.3	8.0	5.8																	0.8			2.5
Pension Plan Funding [Abstract]
Estimated future employer contributions		50
Contributions by employer	10
Estimated employer contributions in current fiscal year	$ 0

[1] In addition to the $7.4 million and $8.0 million of net periodic benefit cost recognized during the three months ended September 30, 2011 and 2010, respectively, OG&E recognized an increase in pension expense during the three months ended September 30, 2011 and 2010 of $2.7 million and $2.3 million, respectively, to maintain the allowable amount to be recovered for pension expense in the Oklahoma jurisdiction which are included in the Pension tracker regulatory liability (see Note 1).

[2] In addition to the $22.3 million and $24.1 million of net periodic benefit cost recognized during the nine months ended September 30, 2011 and 2010, respectively, OG&E recognized an increase in pension expense during the nine months ended September 30, 2011 and 2010 of $8.0 million and $5.8 million, respectively, to maintain the allowable amount to be recovered for pension expense in the Oklahoma jurisdiction which are included in the Pension tracker regulatory liability (see Note 1).

[3] In addition to the $3.9 million and $11.6 million of net periodic benefit cost recognized during the three and nine months ended September 30, 2011, respectively, OG&E recognized an increase in postretirement medical expense during the three and nine months ended September 30, 2011 of $0.8 million and $2.5 million, respectively, to maintain the allowable amount to be recovered for postretirement medical expense in the Oklahoma jurisdiction which are included in the Pension tracker regulatory liability (see Note 1).