Investment in Unconsolidated Affiliates Reconciliation of Equity in Earnings of Unconsolidated Affiliates (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Line Items]
OGE's share of Enable Net Income (Loss)	$ (80.3)		$ 36.4		$ (35.9)		$ 111.1
Amortization of basis difference	3.5		3.4		10.6		10.4
Elimination of Enogex Holdings fair value and other adjustments	4.9		4.9		13.3		10.4
OGE's Equity in earnings of unconsolidated affiliates	$ (71.9)	[1]	$ 44.7	[1]	$ (12.0)	[2]	$ 131.9	[2]

[1] The Company recorded a $108.4 million pre-tax charge during the three months ended September 30, 2015 for its share of Enable's goodwill impairment, as adjusted for the basis differences. See Note 3 for further discussion of Enable's goodwill impairment.

[2] The Company recorded a $108.4 million pre-tax charge during the nine months ended September 30, 2015 for its share of Enable's goodwill impairment, as adjusted for the basis differences. See Note 3 of this Form 10-Q for further discussion of Enable's goodwill impairment.