Common Equity Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 25.2	$ 43.2
Basic Average Common Shares Outstanding	199.7	199.5
Contingently Issuable Shares (Performance and Restricted Stock Units)	0.0	0.0
Diluted Average Common Shares Outstanding	199.7	199.5
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per average common share attributable to OGE Energy common shareholders	$ 0.13	$ 0.22
Diluted earnings per average common share attributable to OGE Energy common shareholders	$ 0.13	$ 0.22
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.0	0.0
Retained Earnings
Net income	$ 25.2	$ 43.2