Summary of Significant Accounting Policies Property. Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 10,814.9		$ 9,648.0
Depreciation and amortization	3,340.9		3,183.6
Property, Plant and Equipment, Net	7,474.0		6,464.4
Public Utilities, Property Plant and Equipment, Amount of Acquistion Adjustments Related Accumulated Amortization	17.9
Cost to Return Plant to Service	29.6
Insurance Deductible	10.0
Proceeds from insurance	7.4		0	0
Gain on insurance proceeds	(3.0)		0	0
Redbud Plant [Member] [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments	148.3
OGE Energy [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	124.6		111.1
Depreciation and amortization	90.6		77.5
Property, Plant and Equipment, Net	34.0		33.6
OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	8,143.2		7,371.7
Depreciation and amortization	2,592.3		2,494.4
Property, Plant and Equipment, Net	5,550.9		4,877.3
Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments	3.3
Enogex [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,547.1		2,165.2
Depreciation and amortization	658.0		611.7
Property, Plant and Equipment, Net	1,889.1		1,553.5
Total Property Plant and Equipment [Member] | OGE Energy [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	124.6		111.1
Depreciation and amortization	90.6		77.5
Property, Plant and Equipment, Net	34.0		33.6
Electric Transmission and Distribution [Member] | OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,981.3		2,833.4
Depreciation and amortization	920.3		897.4
Property, Plant and Equipment, Net	2,061.0		1,936.0
Electric Generation Equipment [Member] | OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,360.6		3,047.1
Depreciation and amortization	1,215.8		1,164.6
Property, Plant and Equipment, Net	2,144.8		1,882.5
Electric Transmission [Member] | OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,464.2		1,221.3
Depreciation and amortization	339.6		325.6
Property, Plant and Equipment, Net	1,124.6		895.7
Finite-Lived Intangible Assets, Major Class Name [Domain] | OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	43.2		26.5
Depreciation and amortization	20.3		20.7
Property, Plant and Equipment, Net	22.9		5.8
Property, Plant and Equipment, Other Types [Member] | OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	293.9		243.4
Depreciation and amortization	96.3		86.1
Property, Plant and Equipment, Net	197.6		157.3
Transportation and Storage [Member] | Enogex [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	956.9		924.7
Depreciation and amortization	271.0		250.0
Property, Plant and Equipment, Net	685.9		674.7
Gas Gathering and Processing Equipment [Member] | Enogex [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,580.1		1,230.8
Depreciation and amortization	381.0		354.6
Property, Plant and Equipment, Net	1,199.1		876.2
Marketing Assets [Member] | Enogex [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	10.1		9.7
Depreciation and amortization	6.0		7.1
Property, Plant and Equipment, Net	4.1		2.6
McClain Plant [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	207.2
Depreciation and amortization	73.7
Property, Plant and Equipment, Net	133.5
McClain Plant [Member] | Ownership Interest in McClain Plant [Member]
Property, Plant and Equipment [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	77.00%
Redbud Plant [Member] [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	461.1	[1]
Depreciation and amortization	54.3	[2]
Property, Plant and Equipment, Net	$ 406.8
Redbud Plant [Member] [Member] | Ownership Interest in Redbud Plant [Member]
Property, Plant and Equipment [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	51.00%

[1] (A) This amount includes a plant acquisition adjustment of $148.3 million.

[2] (B) This amount includes accumulated amortization of the plant acquisition adjustment of $17.9 million.