Noncontrolling Interests Contributions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
OGE Holdings [Member]
Noncontrolling Interest [Line Items]
Ownership percentage, OGE Holdings	79.90%
Contributions Toward Meeting 2013 Capital Requirements	$ 0
ArcLight group [Member]
Noncontrolling Interest [Line Items]
Contributions from noncontrolling interest partner	0
Atoka [Member]
Noncontrolling Interest [Line Items]
Contributions from noncontrolling interest partner	$ 0