Guarantees (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 140.6
Guarantor Obligations, Origin and Purpose	In the ordinary course of business, Great Plains Energy and certain of its subsidiaries enter into various agreements providing financial or performance assurance to third parties on behalf of certain subsidiaries. Such agreements include, for example, guarantees and letters of credit. These agreements are entered into primarily to support or enhance the creditworthiness otherwise attributed to a subsidiary on a stand-alone basis, thereby facilitating the extension of sufficient credit to accomplish the subsidiary's intended business purposes.
Direct Guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	40.7
Guarantor Obligations, Term	expire in 2014 and 2015
Guarantor Obligations, Origin and Purpose	direct guarantees to GMO counterparties
Guarantee of Indebtedness of Others [Member] | Long-term Debt [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	99.9
Guarantor Obligations, Term	maturity dates ranging from 2014-2023
Guarantor Obligations, Origin and Purpose	guarantee of GMO long-term debt
Guarantee of Indebtedness of Others [Member] | Commercial Paper [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 15.0
Guarantor Obligations, Origin and Purpose	guaranteed GMO's commercial paper program