Report of Business Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating revenues	$ 447.1	$ 719.8	$ 549.9	$ 480.1	$ 526.2	$ 754.7	$ 611.8	$ 560.4	$ 2,196.9		$ 2,453.1	$ 2,867.7
Cost of sales									865.0		1,106.6	1,428.9
Other operation and maintenance									451.6		439.6	489.2
Depreciation and amortization									307.9		281.4	297.3
Taxes other than income									91.2		88.7	98.8
Operating income (loss)	46.8	250.8	127.2	56.4	85.1	248.1	141.8	61.8	481.2		536.8	553.5
Equity in earnings of unconsolidated affiliates									15.5	[1]	172.6	101.9
Other income (expense)									21.0		7.6	16.2
Interest expense									149.0		148.4	147.5
Income tax expense (benefit)									97.4		172.8	130.3
NET INCOME	29.4	$ 111.2	$ 87.5	$ 43.2	58.4	$ 187.3	$ 100.8	$ 49.3	271.3		395.8	393.8
Less: Net income attributable to noncontrolling interests									0.0		0.0	6.2
NET INCOME ATTRIBUTABLE TO OGE ENERGY									271.3		395.8	387.6
Investment in unconsolidated affiliates	1,194.4				1,318.2				1,194.4		1,318.2	1,298.8
Total assets	9,597.4				9,527.8				9,597.4		9,527.8	9,134.7
Capital expenditures									547.8		569.3	990.6
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating revenues									2,196.9		2,453.1	2,262.2
Cost of sales									865.0		1,106.6	965.9
Other operation and maintenance									444.5		453.2	438.8
Depreciation and amortization									299.9		270.8	248.4
Taxes other than income									87.1		84.5	83.8
Operating income (loss)									500.4		538.0	525.3
Equity in earnings of unconsolidated affiliates									0.0	[1]	0.0	0.0
Other income (expense)									20.0		7.1	10.1
Interest expense									146.7		141.5	129.3
Income tax expense (benefit)									104.8		111.6	113.5
NET INCOME									268.9		292.0	292.6
Less: Net income attributable to noncontrolling interests												0.0
NET INCOME ATTRIBUTABLE TO OGE ENERGY												292.6
Investment in unconsolidated affiliates	0.0				0.0				0.0		0.0	0.0
Total assets	8,541.8				8,266.2				8,541.8		8,266.2	7,694.9
Capital expenditures									551.6		565.4	797.6
Natural Gas Midstream Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues									0.0		0.0	630.4
Cost of sales									0.0		0.0	489.0
Other operation and maintenance									7.5		1.2	60.9
Depreciation and amortization									0.0		0.0	36.8
Taxes other than income									0.0		0.0	10.5
Operating income (loss)									(7.5)		(1.2)	33.2
Equity in earnings of unconsolidated affiliates									15.5	[1]	172.6	101.9
Other income (expense)									0.4		0.0	8.9
Interest expense									0.0		0.0	10.6
Income tax expense (benefit)									(1.0)		69.1	26.9
NET INCOME									9.4		102.3	106.5
Less: Net income attributable to noncontrolling interests												6.6
NET INCOME ATTRIBUTABLE TO OGE ENERGY												99.9
Investment in unconsolidated affiliates	1,194.4				1,318.2				1,194.4		1,318.2	1,298.8
Total assets	1,439.5				1,461.2				1,439.5		1,461.2	1,348.6
Capital expenditures									0.0		0.0	181.5
Other Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues									0.0		0.0	0.0
Cost of sales									0.0		0.0	0.0
Other operation and maintenance									(0.4)		(14.8)	(10.5)
Depreciation and amortization									8.0		10.6	12.1
Taxes other than income									4.1		4.2	4.5
Operating income (loss)									(11.7)		0.0	(6.1)
Equity in earnings of unconsolidated affiliates									0.0	[1]	0.0	0.0
Other income (expense)									0.9		0.7	(2.3)
Interest expense									2.6		7.1	8.1
Income tax expense (benefit)									(6.4)		(7.9)	(10.6)
NET INCOME									(7.0)		1.5	(5.9)
Less: Net income attributable to noncontrolling interests												0.0
NET INCOME ATTRIBUTABLE TO OGE ENERGY												(5.9)
Investment in unconsolidated affiliates	0.0				0.0				0.0		0.0	0.0
Total assets	175.1				129.2				175.1		129.2	216.2
Capital expenditures									(3.8)		10.8	11.5
Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues									0.0		0.0	(24.9)
Cost of sales									0.0		0.0	(26.0)
Other operation and maintenance									0.0		0.0	0.0
Depreciation and amortization									0.0		0.0	0.0
Taxes other than income									0.0		0.0	0.0
Operating income (loss)									0.0		0.0	1.1
Equity in earnings of unconsolidated affiliates									0.0	[1]	0.0	0.0
Other income (expense)									(0.3)		(0.2)	(0.5)
Interest expense									(0.3)		(0.2)	(0.5)
Income tax expense (benefit)									0.0		0.0	0.5
NET INCOME									0.0		0.0	0.6
Less: Net income attributable to noncontrolling interests												(0.4)
NET INCOME ATTRIBUTABLE TO OGE ENERGY												1.0
Investment in unconsolidated affiliates	0.0				0.0				0.0		0.0	0.0
Total assets	$ (559.0)				$ (328.8)				(559.0)		(328.8)	(125.0)
Capital expenditures									0.0		$ (6.9)	$ 0.0
OGE Energy [Member]
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss									$ 108.4

[1] In September 2015, the Company recorded a $108.4 million pre-tax charge for its share of the goodwill impairment, as adjusted for the basis difference. See Note 3 for further discussion of Enable's goodwill impairment.