Commitments and Contingencies (Details)	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jun. 15, 2015 USD ($)
Loss Contingencies [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 7,400,000
Operating Leases, Future Minimum Payments, Due in Two Years	6,800,000
Operating Leases, Future Minimum Payments, Due in Three Years	5,600,000
Operating Leases, Future Minimum Payments, Due in Four Years	25,500,000
Operating Leases, Future Minimum Payments, Due in Five Years	2,900,000
Operating Leases, Future Minimum Payments, Due Thereafter	46,300,000
Operating Leases, Future Minimum Payments Due	94,500,000
Operating Leases, Rent Expense, Net	7,700,000	$ 6,700,000	$ 8,800,000
Purchase Obligation, Due in Next Twelve Months	752,700,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	441,400,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	338,600,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	198,600,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	169,300,000
Long-term Purchase Commitment, Amount	1,900,600,000
Utilities Operating Expense, Purchased Power under Long-term Contracts	56,600,000	60,800,000	62,000,000
Contract Amount				$ 170,300,000
OG&E Railcar Lease Agreement [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Maximum	20,100,000
OG&E Railcar Lease Agreement [Member]
Loss Contingencies [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	4,200,000
Operating Leases, Future Minimum Payments, Due in Two Years	3,500,000
Operating Leases, Future Minimum Payments, Due in Three Years	2,400,000
Operating Leases, Future Minimum Payments, Due in Four Years	23,000,000
Operating Leases, Future Minimum Payments, Due in Five Years	0
Operating Leases, Future Minimum Payments, Due Thereafter	0
Operating Leases, Future Minimum Payments Due	33,100,000
OG&E Wind Farm Land Lease Agreements [Member]
Loss Contingencies [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	2,400,000
Operating Leases, Future Minimum Payments, Due in Two Years	2,500,000
Operating Leases, Future Minimum Payments, Due in Three Years	2,500,000
Operating Leases, Future Minimum Payments, Due in Four Years	2,500,000
Operating Leases, Future Minimum Payments, Due in Five Years	2,900,000
Operating Leases, Future Minimum Payments, Due Thereafter	46,300,000
Operating Leases, Future Minimum Payments Due	59,100,000
OGE Energy Building Lease [Member]
Loss Contingencies [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	800,000
Operating Leases, Future Minimum Payments, Due in Two Years	800,000
Operating Leases, Future Minimum Payments, Due in Three Years	700,000
Operating Leases, Future Minimum Payments, Due in Four Years	0
Operating Leases, Future Minimum Payments, Due in Five Years	0
Operating Leases, Future Minimum Payments, Due Thereafter	0
Operating Leases, Future Minimum Payments Due	2,300,000
OG&E cogeneration capacity and fixed operation and maintenance payments [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	79,800,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	77,000,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	74,000,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	66,600,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	54,700,000
Long-term Purchase Commitment, Amount	352,100,000
OG&E expected cogeneration energy payments [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	58,300,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	42,700,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	55,200,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	57,600,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	55,100,000
Long-term Purchase Commitment, Amount	268,900,000
OG&E minimum fuel purchase commitments [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	299,600,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	127,500,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	40,700,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	11,700,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	0
Long-term Purchase Commitment, Amount	479,500,000
OG&E expected wind purchase commitments [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	58,600,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	58,800,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	57,000,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	55,800,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	56,600,000
Long-term Purchase Commitment, Amount	286,800,000
OG&E long-term service agreement commitments [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	2,500,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	2,600,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	43,200,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	2,800,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	2,900,000
Long-term Purchase Commitment, Amount	54,000,000
Mustang Modernization expenditures [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	103,400,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	12,900,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	17,700,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	0
Unrecorded Unconditional Purchase Obligation, Due within Five Years	0
Long-term Purchase Commitment, Amount	134,000,000
Environmental compliance plan expenditures [Member]
Loss Contingencies [Line Items]
Purchase Obligation, Due in Next Twelve Months	150,500,000
Unrecorded Unconditional Purchase Obligation, Due within Two Years	119,900,000
Unrecorded Unconditional Purchase Obligation, Due within Three Years	50,800,000
Unrecorded Unconditional Purchase Obligation, Due within Four Years	4,100,000
Unrecorded Unconditional Purchase Obligation, Due within Five Years	0
Long-term Purchase Commitment, Amount	$ 325,300,000
Public Utility Regulatory Policy Act of 1978 [Member]
Loss Contingencies [Line Items]
Percentage of output purchased	100.00%
OG&E total cogeneration payments [Member]
Loss Contingencies [Line Items]
Long-term Purchase Commitment, Amount	$ 124,000,000	129,400,000	134,800,000
OG&E capacity payments [Member]
Loss Contingencies [Line Items]
Long-term Purchase Commitment, Amount	69,500,000	72,300,000	74,400,000
CPV Keenan [Member]
Loss Contingencies [Line Items]
Utilities Operating Expense, Purchased Power under Long-term Contracts	26,700,000	28,100,000	30,900,000
Edison Mission Energy [Member]
Loss Contingencies [Line Items]
Utilities Operating Expense, Purchased Power under Long-term Contracts	19,700,000	21,300,000	20,600,000
FPL Energy [Member]
Loss Contingencies [Line Items]
Utilities Operating Expense, Purchased Power under Long-term Contracts	3,200,000	3,600,000	3,300,000
NextEra Energy [Member]
Loss Contingencies [Line Items]
Utilities Operating Expense, Purchased Power under Long-term Contracts	$ 7,000,000	$ 7,800,000	$ 7,200,000
OG&E long-term service agreement commitments [Member] | McClain Plant [Member]
Loss Contingencies [Line Items]
Factored-Fired Hours	128,000
Factored-Fired Starts	4,800
OG&E long-term service agreement commitments [Member] | Redbud Plant [Member]
Loss Contingencies [Line Items]
Factored-Fired Hours	144,000
Factored-Fired Starts	4,500
Additional Factored-Fired Hours	24,000
New Source Review [Member]
Loss Contingencies [Line Items]
Estimated Environmental Capital Costs	$ 1,100,000,000
Potential Penalty Under the Federal Clean Air Act	$ 37,500
Clean Power Plan [Member]
Loss Contingencies [Line Items]
Proposed Rate-Based Carbon Reduction	43.00%
Final Rate-Based Carbon Reduction	32.00%
Mass-Based Carbon Reduction	24.00%