Receivables Narrative (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount	$ 190.0	$ 95.0
Kansas City Power and Light Company [Member]
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount	110.0	95.0
Maximum percentage servicing fee received on receivables sold (in hundredths)	1.50%
Maximum amount of outstanding principal under receivables agreement	110
KCPL Greater Missouri Operations [Member]
Maximum percentage servicing fee received on receivables sold (in hundredths)	1.25%
Maximum amount of outstanding principal under receivables agreement from June 1 to October 31 of each year	80
Maximum amount of outstanding principal under receivables agreement from November 1 to May 31 of each year	$ 65