Report of Business Segments (Details) - USD ($) $ in Millions	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Segment Reporting Information [Line Items]
Operating revenues	$ 530.8	$ 743.9	$ 551.4	$ 433.1	$ 447.1	$ 719.8	$ 549.9	$ 480.1		$ 2,259.2	$ 2,196.9		$ 2,453.1
Cost of sales										880.1	865.0		1,106.6
Other operation and maintenance										465.6	451.6		439.6
Depreciation and amortization										322.6	307.9		281.4
Taxes other than income										87.6	91.2		88.7
Operating income (loss)	82.2	257.3	125.9	37.9	46.8	250.8	127.2	56.4		503.3	481.2		536.8
Equity in earnings of unconsolidated affiliates										101.8	15.5	[1]	172.6
Other income (expense)										23.3	21.0		7.6
Interest expense										142.1	149.0		148.4
Income tax expense (benefit)										148.1	97.4		172.8
NET INCOME	57.9	$ 183.6	$ 71.5	$ 25.2	29.4	$ 111.2	$ 87.5	$ 43.2		338.2	271.3		395.8
NET INCOME ATTRIBUTABLE TO OGE ENERGY										338.2	271.3		395.8
Investment in unconsolidated affiliates	1,158.6				1,194.4					1,158.6	1,194.4		1,318.2
Total assets	9,939.6				9,580.6					9,939.6	9,580.6		9,509.9
Capital expenditures										660.1	547.8		569.3
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating revenues										2,259.2	2,196.9		2,453.1
Cost of sales										880.1	865.0		1,106.6
Other operation and maintenance										469.8	444.5		453.2
Depreciation and amortization										316.4	299.9		270.8
Taxes other than income										84.0	87.1		84.5
Operating income (loss)										508.9	500.4		538.0
Equity in earnings of unconsolidated affiliates										0.0	0.0	[1]	0.0
Other income (expense)										27.7	20.0		7.1
Interest expense										138.1	146.7		141.5
Income tax expense (benefit)										114.4	104.8		111.6
NET INCOME										284.1	268.9		292.0
Investment in unconsolidated affiliates	0.0				0.0					0.0	0.0		0.0
Total assets	8,669.4				8,525.5					8,669.4	8,525.5		8,248.9
Capital expenditures										660.1	551.6		565.4
Natural Gas Midstream 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										7.7	7.5		1.2
Depreciation and amortization										0.0	0.0		0.0
Taxes other than income										0.0	0.0		0.0
Operating income (loss)										(7.7)	(7.5)		(1.2)
Equity in earnings of unconsolidated affiliates										101.8	15.5	[1]	172.6
Other income (expense)										0.1	0.4		0.0
Interest expense										0.0	0.0		0.0
Income tax expense (benefit)										40.5	(1.0)		69.1
NET INCOME										53.7	9.4		102.3
Investment in unconsolidated affiliates	1,158.6				1,194.4					1,158.6	1,194.4		1,318.2
Total assets	1,521.6				1,439.5					1,521.6	1,439.5		1,461.2
Capital expenditures										0.0	0.0		0.0
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										(11.9)	(0.4)		(14.8)
Depreciation and amortization										6.2	8.0		10.6
Taxes other than income										3.6	4.1		4.2
Operating income (loss)										2.1	(11.7)		0.0
Equity in earnings of unconsolidated affiliates										0.0	0.0	[1]	0.0
Other income (expense)										(4.3)	0.9		0.7
Interest expense										4.2	2.6		7.1
Income tax expense (benefit)										(6.8)	(6.4)		(7.9)
NET INCOME										0.4	(7.0)		1.5
Investment in unconsolidated affiliates	0.0				0.0					0.0	0.0		0.0
Total assets	89.0				174.6					89.0	174.6		128.6
Capital expenditures										0.0	(3.8)		10.8
Eliminations [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										0.0	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		0.0
Equity in earnings of unconsolidated affiliates										0.0	0.0	[1]	0.0
Other income (expense)										(0.2)	(0.3)		(0.2)
Interest expense										(0.2)	(0.3)		(0.2)
Income tax expense (benefit)										0.0	0.0		0.0
NET INCOME										0.0	0.0		0.0
Investment in unconsolidated affiliates	0.0				0.0					0.0	0.0		0.0
Total assets	$ (340.4)				$ (559.0)					(340.4)	(559.0)		(328.8)
Capital expenditures										0.0	0.0		$ (6.9)
OGE Energy [Member]
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss									$ 108.4	$ (2.6)	$ (178.4)

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