Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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The proportionate share of interest (percent) in a jointly owned utility plant.

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Amount of transactions with related party during the financial reporting period.

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Receivables to be collected from (obligations owed to) related parties, net as of the balance sheet date within one year where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Related Party Transactions and Relationships (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Westar Energy Inc [Member] \| KCPL Greater Missouri Operations [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	$ 2.6	$ 0.0
Westar Energy Inc [Member] \| KCPL [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	(13.5)	0.0
Westar Energy Inc [Member] \| KCPL [Member] \| Operating Expenses and Capital Costs Billed [Member]
Related Party Transaction [Line Items]
Related party transaction	17.5
Westar Energy Inc [Member] \| Evergy [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	(1.4)	0.0
Westar Energy Inc [Member] \| Evergy [Member] \| Income Taxes Payable [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	42.7
KCPL [Member] \| Money Pool [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	0.0	0.0
KCPL [Member] \| KCPL Greater Missouri Operations [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	72.6	65.8
KCPL [Member] \| Westar Energy Inc [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	13.5	0.0
KCPL [Member] \| Evergy [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	15.7	0.0
KCPL [Member] \| Evergy [Member] \| Income Taxes Payable [Member]
Related Party Transaction [Line Items]
Due to related parties	(2.0)
KCPL [Member] \| Great Plains Energy [Member]
Related Party Transaction [Line Items]
Due from (to) related parties	$ 0.0	18.9
Iatan No 1 And 2 [Member] \| KCPL Greater Missouri Operations [Member]
Related Party Transaction [Line Items]
Jointly owned utility plant, proportionate ownership share	18.00%
Iatan No 1 And 2 [Member] \| KCPL [Member] \| KCPL Greater Missouri Operations [Member] \| Operating Expenses and Capital Costs Billed [Member]
Related Party Transaction [Line Items]
Related party transaction	$ 183.2	$ 196.3	$ 194.4
Jeffrey Energy Center [Member] \| KCPL Greater Missouri Operations [Member]
Related Party Transaction [Line Items]
Jointly owned utility plant, proportionate ownership share	8.00%
Jeffrey Energy Center [Member] \| Westar Energy Inc [Member] \| KCPL Greater Missouri Operations [Member] \| Operating Expenses and Capital Costs Billed [Member]
Related Party Transaction [Line Items]
Related party transaction	$ 12.3
La Cygne Station [Member] \| Westar Energy Inc [Member]
Related Party Transaction [Line Items]
Jointly owned utility plant, proportionate ownership share	50.00%
La Cygne Station [Member] \| KCPL [Member] \| Westar Energy Inc [Member] \| Operating Expenses and Capital Costs Billed [Member]
Related Party Transaction [Line Items]
Related party transaction	$ 82.9