Regulatory Matters Regulatory Matters Subsequent Events (Details) - Kansas City Power and Light Company [Member] - Subsequent Event [Member] - USD ($) $ in Millions	1 Months Ended
	May 31, 2017	Apr. 30, 2017
MissouriPublicServiceCommission [Member]
Subsequent Event [Line Items]
Return on equity, approved (in hundredths)	9.50%
Ratemaking equity ratio, approved (in hundredths)	49.20%
Kansas Corporation Commission [Member]
Subsequent Event [Line Items]
Public Utilities, KCPL and Commission Staff Recommended Rate Decrease, Amount		$ 3.6
Minimum [Member] | MissouriPublicServiceCommission [Member]
Subsequent Event [Line Items]
Anticipated annual revenue increase authorized	$ 30.0
Maximum [Member] | MissouriPublicServiceCommission [Member]
Subsequent Event [Line Items]
Anticipated annual revenue increase authorized	$ 35.0