Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Operating revenues	$ 530.8		$ 743.9		$ 551.4		$ 433.1		$ 447.1		$ 719.8		$ 549.9		$ 480.1		$ 2,259.2		$ 2,196.9		$ 2,453.1
Operating income	82.2		257.3		125.9		37.9		46.8		250.8		127.2		56.4		503.3		481.2		536.8
Net income	$ 57.9		$ 183.6		$ 71.5		$ 25.2		$ 29.4		$ 111.2		$ 87.5		$ 43.2		$ 338.2		$ 271.3		$ 395.8
Basic earnings per average common share attributable to OGE Energy common shareholders	$ 0.29	[1]	$ 0.92	[1]	$ 0.35	[1]	$ 0.13	[1]	$ 0.15	[1]	$ 0.55	[1]	$ 0.44	[1]	$ 0.22	[1]	$ 1.69	[1]	$ 1.36	[1]	$ 1.99
Diluted earnings per average common share attributable to OGE Energy common shareholders	$ 0.29	[1]	$ 0.92	[1]	$ 0.35	[1]	$ 0.13	[1]	$ 0.15	[1]	$ 0.55	[1]	$ 0.44	[1]	$ 0.22	[1]	$ 1.69	[1]	$ 1.36	[1]	$ 1.98

[1] Due to the impact of dilution on the earnings per share calculation, quarterly earnings per share amounts may not add to the total.