Summary of Significant Accounting Policies Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 14,151.8		$ 13,442.2
Accumulated Depreciation	4,318.9		4,067.6
Net property, plant and equipment	9,832.9		9,374.6
Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments, Related Accumulated Depreciation	$ 72.8		$ 67.3
Provision for Depreciation Rate	2.60%		2.60%
McClain Plant [Member]
Property, Plant and Equipment [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	77.00%	[1]	77.00%	[2]
Property, Plant and Equipment, Gross	$ 258.5	[1]	$ 257.1	[2]
Accumulated Depreciation	109.0	[1]	96.0	[2]
Net property, plant and equipment	149.5	[1]	161.1	[2]
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 0.2		$ 0.1
Redbud Plant [Member]
Property, Plant and Equipment [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	51.00%	[1],[3]	51.00%	[2],[4]
Property, Plant and Equipment, Gross	$ 538.2	[1],[3]	$ 531.8	[2],[4]
Accumulated Depreciation	203.4	[1],[3]	181.9	[2],[4]
Net property, plant and equipment	334.8	[1],[3]	349.9	[2],[4]
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	0.2		1.8
Amount of Acquisition Adjustments	148.3		148.3
OGE Energy [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	6.1		6.1
Accumulated Depreciation	0.0		0.0
Net property, plant and equipment	6.1		6.1
OG&E [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	14,145.7		13,436.1
Accumulated Depreciation	4,318.9		4,067.6
Net property, plant and equipment	9,826.8		9,368.5
Capitalized Computer Software, Gross	103.7		89.7
Capitalized Computer Software, Amortization	18.1		14.9		$ 11.0
OG&E [Member] | Total Property Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	14,145.7		13,436.1
Accumulated Depreciation	4,318.9		4,067.6
Net property, plant and equipment	9,826.8		9,368.5
OG&E [Member] | Electric Transmission and Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	5,225.8		4,809.9
Accumulated Depreciation	1,477.5		1,422.1
Net property, plant and equipment	3,748.3		3,387.8
OG&E [Member] | Electric Generation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	5,037.9	[5]	4,932.2	[6]
Accumulated Depreciation	1,839.0	[5]	1,713.6	[6]
Net property, plant and equipment	3,198.9	[5]	3,218.6	[6]
Amount of Acquisition Adjustments	148.3		148.3
Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments, Related Accumulated Depreciation	72.8		67.3
OG&E [Member] | Electric Transmission [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,038.2	[7]	2,944.6	[8]
Accumulated Depreciation	627.0	[7]	591.7	[8]
Net property, plant and equipment	2,411.2	[7]	2,352.9	[8]
Amount of Acquisition Adjustments	3.3		3.3
Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments, Related Accumulated Depreciation	0.9		0.9
OG&E [Member] | Finite-Lived Intangible Assets, Major Class Name [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	301.1		254.1
Accumulated Depreciation	171.7		153.9
Net property, plant and equipment	129.4		100.2
OG&E [Member] | Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	542.7		495.3
Accumulated Depreciation	203.7		186.3
Net property, plant and equipment	$ 339.0		$ 309.0

[1] Construction work in progress was $0.2 million and $0.2 million for the McClain and Redbud Plants, respectively.

[2] Construction work in progress was $0.1 million and $1.8 million for the McClain and Redbud Plants, respectively.

[3] This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $72.8 million.

[4] This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.

[5] This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $72.8 million.

[6] This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.

[7] This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.9 million.

[8] This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.9 million.