Common Equity Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Equity [Abstract]
Net Income Attributable to OGE Energy	$ 36.4	$ 178.7	$ 103.0	$ 24.8	$ 30.7	$ 163.1	$ 77.3	$ 24.2	$ 342.9	$ 295.3	$ 258.3
Basic Average Common Shares Outstanding									97.9	97.3	96.2
Contingently Issuable Shares (Performance Units)									1.3	1.6	1.0
Diluted Average Common Shares Outstanding									99.2	98.9	97.2
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per average common share attributable to OGE Energy common shareholders	$ 0.37	$ 1.82	$ 1.05	$ 0.25	$ 0.32	$ 1.67	$ 0.79	$ 0.25	$ 3.50	$ 3.03	$ 2.68
Diluted earnings per average common share attributable to OGE Energy common shareholders	$ 0.37	$ 1.80	$ 1.04	$ 0.25	$ 0.31	$ 1.65	$ 0.78	$ 0.25	$ 3.45	$ 2.99	$ 2.66
Anti-dilutive shares excluded from earnings per share calculation									0	0	0