Regulatory Matters (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Kansas City Power and Light Company [Member] | Kansas Corporation Commission [Member]
Regulatory Proceedings [Line Items]
Annual revenue increase, requested	$ 12.1
Revised annual revenue increase, requested	11.5
KCPL Greater Missouri Operations [Member] | Missouri Public Service Commission [Member] | St Joseph Light and Power division [Member]
Regulatory Proceedings [Line Items]
Annual revenue increase authorized	21.7
KCPL Greater Missouri Operations [Member] | Missouri Public Service Commission [Member] | Missouri Public Service division [Member]
Regulatory Proceedings [Line Items]
Annual revenue increase authorized	$ 26.2