Regulatory Matters (Details) (USD $)	3 Months Ended	12 Months Ended	0 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013	Feb. 27, 2013 Missouri Public Service Commission (MPSC) Missouri 2012 Rate Case	Mar. 31, 2013 Missouri Public Service Commission (MPSC) Missouri 2012 Rate Case	Mar. 31, 2013 Missouri Public Service Commission (MPSC) Missouri 2012 Rate Case Latan 2	Feb. 27, 2013 Missouri Public Service Commission (MPSC) Electric Missouri 2012 Rate Case
RATE MATTERS
Approved amount of annual increase in base rate						$ 27,500,000
Deferred tornado costs recovery period			10 years
Write-off of various items				3,600,000
Write-off of various items					2,400,000
Reverse gain on sale of Asbury unit train	$ 1,236,000	$ 1,236,000		$ 1,200,000