Report of Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating revenues	$ 754.7	$ 723.2	$ 1,926.9	$ 2,358.8
Cost of sales	305.3	273.0	869.6	1,196.6
Other operation and maintenance	108.1	102.2	331.9	372.2
Depreciation and amortization	71.7	65.4	207.2	231.7
Taxes other than income	21.5	21.7	66.5	78.1
OPERATING INCOME	248.1	260.9	451.7	480.2
Equity in earnings of unconsolidated affiliates	44.7	46.0	131.9	64.5
Other income (expense)	2.5	2.7	3.5	13.9
Interest expense	37.2	33.7	112.5	112.2
Income Tax Expense	70.8	60.7	137.2	110.2
NET INCOME	187.3	215.2	337.4	336.2
Less: Net income attributable to noncontrolling interests	0	0	0	6.2
Net income attributable to OGE Energy	187.3	215.2	337.4	330.0
Investment in unconsolidated affiliates	1,311.1	1,295.8	1,311.1	1,295.8	1,298.8
Total assets	9,462.7	9,144.2	9,462.7	9,144.2	9,134.7
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating revenues	754.7	723.2	1,926.9	1,753.3
Cost of sales	305.3	273.0	869.6	733.6
Other operation and maintenance	111.0	105.9	343.1	318.0
Depreciation and amortization	69.4	62.5	198.7	185.8
Taxes other than income	20.6	20.8	63.1	63.9
OPERATING INCOME	248.4	261.0	452.4	452.0
Equity in earnings of unconsolidated affiliates	0	0	0	0
Other income (expense)	2.9	4.1	4.5	9.5
Interest expense	35.3	31.6	106.7	96.0
Income Tax Expense	58.7	62.0	95.3	102.0
NET INCOME	157.3	171.5	254.9	263.5
Less: Net income attributable to noncontrolling interests				0
Net income attributable to OGE Energy				263.5
Investment in unconsolidated affiliates	0	0	0	0
Total assets	8,003.1	7,704.0	8,003.1	7,704.0
Natural Gas Midstream Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	630.4
Cost of sales	0	0	0	489.0
Other operation and maintenance	0.3	0	0.7	60.9
Depreciation and amortization	0	0	0	36.8
Taxes other than income	0	0	0	10.5
OPERATING INCOME	(0.3)	0	(0.7)	33.2
Equity in earnings of unconsolidated affiliates	44.7	46.0	131.9	64.5
Other income (expense)	0	0	0	8.9
Interest expense	0	0	0	10.6
Income Tax Expense	16.2	0.2	49.6	16.5
NET INCOME	28.2	45.8	81.6	79.5
Less: Net income attributable to noncontrolling interests				6.6
Net income attributable to OGE Energy				72.9
Investment in unconsolidated affiliates	1,311.1	1,295.8	1,311.1	1,295.8
Total assets	1,427.2	1,311.3	1,427.2	1,311.3
Other Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Cost of sales	0	0	0	0
Other operation and maintenance	(3.2)	(3.7)	(11.9)	(6.7)
Depreciation and amortization	2.3	2.9	8.5	9.1
Taxes other than income	0.9	0.9	3.4	3.7
OPERATING INCOME	0	(0.1)	0	(6.1)
Equity in earnings of unconsolidated affiliates	0	0	0	0
Other income (expense)	(0.3)	(1.4)	(0.8)	(4.0)
Interest expense	2.0	2.1	6.0	6.1
Income Tax Expense	(4.1)	(1.6)	(7.7)	(8.9)
NET INCOME	1.8	(2.0)	0.9	(7.3)
Less: Net income attributable to noncontrolling interests				0
Net income attributable to OGE Energy				(7.3)
Investment in unconsolidated affiliates	0	0	0	0
Total assets	204.1	172.2	204.1	172.2
Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	(24.9)
Cost of sales	0	0	0	(26.0)
Other operation and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
Taxes other than income	0	0	0	0
OPERATING INCOME	0	0	0	1.1
Equity in earnings of unconsolidated affiliates	0	0	0	0
Other income (expense)	(0.1)	0	(0.2)	(0.5)
Interest expense	(0.1)	0	(0.2)	(0.5)
Income Tax Expense	0	0.1	0	0.6
NET INCOME	0	(0.1)	0	0.5
Less: Net income attributable to noncontrolling interests				(0.4)
Net income attributable to OGE Energy				0.9
Investment in unconsolidated affiliates	0	0	0	0
Total assets	$ (171.7)	$ (43.3)	$ (171.7)	$ (43.3)