Report of Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating revenues	$ 526.2	$ 754.7	$ 611.8	$ 560.4	$ 508.9	$ 723.2	$ 734.2	$ 901.4	$ 2,453.1	$ 2,867.7	$ 3,671.2
Cost of sales									1,106.6	1,428.9	1,918.7
Other operation and maintenance									439.6	489.2	601.5
Depreciation and amortization									281.4	297.3	371.4
Gain on insurance proceeds									0	0	(7.5)
Taxes other than income									88.7	98.8	110.2
Operating income (loss)	85.1	248.1	141.8	61.8	73.3	260.9	143.9	75.4	536.8	553.5	676.9
Equity in earnings of unconsolidated affiliates									172.6	101.9	0
Other income (expense)									7.6	16.2	7.3
Interest expense									148.4	147.5	164.1
Income tax expense									172.8	130.3	135.1
NET INCOME	58.4	187.3	100.8	49.3	57.6	215.2	93.0	28.0	395.8	393.8	385.0
Less: Net income attributable to noncontrolling interests									0	6.2	30.0
NET INCOME ATTRIBUTABLE TO OGE ENERGY	58.4	187.3	100.8	49.3	57.6	215.2	91.7	23.1	395.8	387.6	355.0
Investment in unconsolidated affiliates (at historical cost)	1,318.2				1,298.8				1,318.2	1,298.8
Total assets	9,527.8				9,134.7				9,527.8	9,134.7	9,922.2
Capital expenditures									569.3	990.6	1,229.2
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating revenues									2,453.1	2,262.2	2,141.2
Cost of sales									1,106.6	965.9	879.1
Other operation and maintenance									453.2	438.8	446.3
Depreciation and amortization									270.8	248.4	248.7
Gain on insurance proceeds											0
Taxes other than income									84.5	83.8	77.7
Operating income (loss)									538.0	525.3	489.4
Equity in earnings of unconsolidated affiliates									0	0
Other income (expense)									7.1	10.1	10.1
Interest expense									141.5	129.3	124.6
Income tax expense									111.6	113.5	94.6
NET INCOME									292.0	292.6	280.3
Less: Net income attributable to noncontrolling interests										0	0
NET INCOME ATTRIBUTABLE TO OGE ENERGY										292.6	280.3
Investment in unconsolidated affiliates (at historical cost)	0				0				0	0
Total assets	8,266.2				7,694.9				8,266.2	7,694.9	7,222.4
Capital expenditures									565.4	797.6	704.4
Natural Gas Midstream Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues									0	630.4	1,608.6
Cost of sales									0	489.0	1,120.1
Other operation and maintenance									1.2	60.9	172.9
Depreciation and amortization									0	36.8	109.2
Gain on insurance proceeds											(7.5)
Taxes other than income									0	10.5	28.3
Operating income (loss)									(1.2)	33.2	185.6
Equity in earnings of unconsolidated affiliates									172.6	101.9
Other income (expense)									0	8.9	(3.5)
Interest expense									0	10.6	32.6
Income tax expense									69.1	26.9	45.7
NET INCOME									102.3	106.5	103.8
Less: Net income attributable to noncontrolling interests										6.6	29.7
NET INCOME ATTRIBUTABLE TO OGE ENERGY										99.9	74.1
Investment in unconsolidated affiliates (at historical cost)	1,318.2				1,298.8				1,318.2	1,298.8
Total assets	1,461.2				1,348.6				1,461.2	1,348.6	2,681.3
Capital expenditures									0	181.5	506.5
Other Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues									0	0	0
Cost of sales									0	0	0
Other operation and maintenance									(14.8)	(10.5)	(17.7)
Depreciation and amortization									10.6	12.1	13.5
Gain on insurance proceeds											0
Taxes other than income									4.2	4.5	4.2
Operating income (loss)									0	(6.1)	0
Equity in earnings of unconsolidated affiliates									0	0
Other income (expense)									0.7	(2.3)	1.8
Interest expense									7.1	8.1	8.0
Income tax expense									(7.9)	(10.6)	(5.8)
NET INCOME									1.5	(5.9)	(0.4)
Less: Net income attributable to noncontrolling interests										0	0
NET INCOME ATTRIBUTABLE TO OGE ENERGY										(5.9)	(0.4)
Investment in unconsolidated affiliates (at historical cost)	0				0				0	0
Total assets	129.2				216.2				129.2	216.2	242.6
Capital expenditures									10.8	11.5	18.3
Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues									0	(24.9)	(78.6)
Cost of sales									0	(26.0)	(80.5)
Other operation and maintenance									0	0	0
Depreciation and amortization									0	0	0
Gain on insurance proceeds											0
Taxes other than income									0	0	0
Operating income (loss)									0	1.1	1.9
Equity in earnings of unconsolidated affiliates									0	0
Other income (expense)									(0.2)	(0.5)	(1.1)
Interest expense									(0.2)	(0.5)	(1.1)
Income tax expense									0	0.5	0.6
NET INCOME									0	0.6	1.3
Less: Net income attributable to noncontrolling interests										(0.4)	0.3
NET INCOME ATTRIBUTABLE TO OGE ENERGY										1.0	1.0
Investment in unconsolidated affiliates (at historical cost)	0				0				0	0
Total assets	(328.8)				(125.0)				(328.8)	(125.0)	(224.1)
Capital expenditures									$ (6.9)	$ 0	$ 0