RECEIVABLES - Other Receivables (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables, contracts with customers	$ 85.7	$ 57.5
Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables, contracts with customers	70.5	49.9
Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables, contracts with customers	$ 13.8	$ 6.9