Common Equity Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Equity [Abstract]
Net Income Attributable to OGE Energy	$ 23.1	$ 37.1
Basic Average Common Shares Outstanding	98.9	98.3
Contingently Issuable Shares (Performance Units)	0.5	0.5
Diluted Average Common Shares Outstanding	99.4	98.8
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per average common share attributable to OGE Energy common shareholders	$ 0.23	$ 0.38
Diluted earnings per average common share attributable to OGE Energy common shareholders	$ 0.23	$ 0.38
Anti-dilutive shares excluded from earnings per share calculation	0	0