Commitments and Contingencies Other Purchase Obligations and Commitments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended								60 Months Ended
	Mar. 31, 2012	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2016	Jun. 30, 2011
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due							$ 53.2
Operating Leases, Future Minimum Payments Due, Current							6.8
Operating Leases, Future Minimum Payments, Due in Two Years							5.9
Operating Leases, Future Minimum Payments, Due in Three Years							5.2
Operating Leases, Future Minimum Payments, Due in Four Years							5.1
Operating Leases, Future Minimum Payments, Due in Five Years							29.6
Operating Leases, Future Minimum Payments, Due Thereafter							0.6
Square Footage of Executive Offices							116,184				134,219
Lease Term for Enogex Executive Offices											5
Long-term Purchase Commitment, Amount		210.5	293.6	334.3	401.8	579.0				1,819.2
Operating Leases, Rent Expense, Net							9.5	9.4	9.2
Percentage of output purchased							100.00%
Long-term Purchase Commitment, Amount							36.7	7.7	4.0
Percentage of OG&E's projected 2012 natural gas requirements	26.00%
Ownership Interest in McClain Plant							77.00%
Ownership Interest in Redbud Plant							51.00%
Initial capacity							60,000
Initial annual demand fee							7.4
Initial capacity turned back							20,000
Firm Capacity							10,000
Annual Demand Fee							2.1
OG&E cogeneration capacity and fixed operation and maintenance payments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		83.3	85.2	87.3	89.4	90.3				435.5
OG&E expected cogeneration energy payments [Member] [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		86.8	74.2	81.3	68.9	59.3				370.5
OG&E minimum fuel purchase commitments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		0	90.4	87.9	192.4	380.2	647.6	721.4	588.3	750.9
OG&E expected wind purchase commitments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		34.7	34.0	33.3	32.8	32.4				167.2
OG&E long-term service agreement commitments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		5.0	5.1	33.7	6.6	4.5				54.9
OER Cheyenne Plains commitments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		0	1.6	6.5	6.5	5.3				19.9
OER MEP commitments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		0	0	1.2	2.1	2.1				5.4
OER other commitments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount		0.7	3.1	3.1	3.1	4.9				14.9
OG&E total cogeneration payments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount							140.7	147.3	139.8
OG&E capacity payments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount							78.0	80.7	83.1
CPV Keenan [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount							24.5	3.8	0
Edison Mission Energy [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount							8.5	0	0
FPL Energy [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Amount							3.7	3.9	4.0
McClain Plant [Member]
Long-term Purchase Commitment [Line Items]
Factor-Fired Hours							96,000
Factor-Fired Starts							4,800
Redbud Plant [Member] [Member]
Long-term Purchase Commitment [Line Items]
Factor-Fired Hours							120,000
Factor-Fired Starts							4,500
Enogex Building Lease [Member]
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due							11.3
OG&E Railcar Lease Agreement [Member]
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due							38.7
Operating Leases, Future Minimum Payments Due, Current							2.9
Operating Leases, Future Minimum Payments, Due in Two Years							2.9
Operating Leases, Future Minimum Payments, Due in Three Years							2.8
Operating Leases, Future Minimum Payments, Due in Four Years							2.7
Operating Leases, Future Minimum Payments, Due in Five Years							27.4
Operating Leases, Future Minimum Payments, Due Thereafter							0
Enogex Noncancellable Operating Leases [Member]
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due							14.5
Operating Leases, Future Minimum Payments Due, Current							3.9
Operating Leases, Future Minimum Payments, Due in Two Years							3.0
Operating Leases, Future Minimum Payments, Due in Three Years							2.4
Operating Leases, Future Minimum Payments, Due in Four Years							2.4
Operating Leases, Future Minimum Payments, Due in Five Years							2.2
Operating Leases, Future Minimum Payments, Due Thereafter							$ 0.6