Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

Future minimum payments for noncancellable operating leases are as follows:



Year Ended December 31 (In millions)	2018		2019		2020		2021		2022		After 2022		Total
Operating lease obligations:
Railcars	$	1.7	$	20.9	$	—	$	—	$	—	$	—	$	22.6
Wind farm land leases	2.5		2.5		2.9		2.9		2.9		40.6		54.3
Noncancellable operating lease	0.6		—		—		—		—		—		0.6
Total operating lease obligations	$	4.8	$	23.4	$	2.9	$	2.9	$	2.9	$	40.6	$	77.5

Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block]

The Company's other future purchase obligations and commitments estimated for the next five years are as follows:



(In millions)	2018		2019		2020		2021		2022		Total
Other purchase obligations and commitments:
Cogeneration capacity and fixed operation and maintenance payments	$	72.8	$	65.3	$	53.2	$	49.5	$	45.4	$	286.2
Expected cogeneration energy payments	35.7		35.6		35.9		37.1		38.3		182.6
Minimum fuel purchase commitments	139.8		36.2		24.6		24.6		24.6		249.8
Expected wind purchase commitments	58.7		56.5		56.9		57.3		57.8		287.2
Long-term service agreement commitments	7.9		41.9		2.4		2.4		2.4		57.0
Mustang Modernization expenditures	24.9		—		—		—		—		24.9
Environmental compliance plan expenditures	63.0		8.9		0.2		—		—		72.1
Total other purchase obligations and commitments	$	402.8	$	244.4	$	173.2	$	170.9	$	168.5	$	1,159.8

Schedule of Wind Power Purchases [Table Text Block]

OG&E owns the 120 MW Centennial, 101 MW OU Spirit and 228 MW Crossroads wind farms. OG&E's current wind power portfolio also includes purchase power contracts with the following:



Company	Location	Term of Contract	Expiration of Contract	MWs
CPV Keenan	Woodward County, OK	20 years	2030	152.0
Edison Mission Energy	Dewey County, OK	20 years	2031	130.0
NextEra Energy	Blackwell, OK	20 years	2032	60.0
FPL Energy	Woodward, OK	15 years	2018	50.0

The following table summarizes OG&E's wind power purchases for the years ended December 31, 2017, 2016 and 2015.



Year Ended December 31 (In millions)	2017		2016		2015
CPV Keenan	$	29.0	$	29.2	$	26.7
Edison Mission Energy	22.1		21.1		19.7
NextEra Energy	7.4		7.3		7.0
FPL Energy	2.6		3.4		3.2
Total wind power purchased	$	61.1	$	61.0	$	56.6