RECEIVABLES - Pledged as Collateral (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 395.0	$ 339.0
Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	200.0	171.0
Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable pledged as collateral	$ 130.0	$ 118.0