RECEIVABLES - Other Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables, contracts with customers	$ 58.8	$ 42.0
Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables, contracts with customers	49.9	37.7
Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables, contracts with customers	$ 6.1	$ 1.2