Common Equity Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Equity [Abstract]
Net Income Attributable to OGE Energy	$ 49.3	$ 23.1
Basic average common shares outstanding	198.8	197.8
Contingently issuable shares (performance units)	0.7	1.0
Diluted average common shares outstanding	199.5	198.8
Earnings Per Share, Basic and Diluted [Abstract]
Basic Earnings Per Average Common Share Attributable to OGE Energy Common Shareholders	$ 0.25	$ 0.12
Diluted Earnings Per Average Common Share Attributable to OGE Energy Common Shareholders	$ 0.25	$ 0.12
Anti-dilutive shares excluded from earnings per share calculation	0	0