Regulatory Matters Regulatory Matters Subsequent Events (Details) (Kansas City Power and Light Company [Member], Missouri Public Service Commission [Member], Subsequent Event [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
	Oct. 31, 2014
Kansas City Power and Light Company [Member] | Missouri Public Service Commission [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Annual revenue increase, requested	$ 120.9
Return on equity, requested (in hundredths)	10.30%
Rate-making equity ratio, requested (in hundredths)	50.36%