Investment in Unconsolidated Affiliate and Related Party Transactions Reconciliation of Equity in Earnings of Unconsolidated Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
OGE's share of Enable Net Income (Loss)	$ (16.0)		$ 143.1
Amortization of basis difference	13.5		14.0
Elimination of Enogex Holdings fair value and other adjustments	18.0		15.5
Equity in earnings of unconsolidated affiliates	15.5	[1]	172.6	$ 101.9
Natural Gas Midstream Operations [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings of unconsolidated affiliates	$ 15.5	[1]	$ 172.6	$ 101.9

[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.