RECEIVABLES (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	$ 205.1	$ 177.9
Allowance for credit losses	(23.6)	(19.3)
Total	247.5	273.9
Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	200.9	175.7
Allowance for credit losses	(8.8)	(7.5)
Total	209.1	218.9
Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	26.4	21.9
Allowance for credit losses	(9.9)	(8.1)
Total	37.9	45.0
Customer accounts receivable | Billed
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer accounts receivable	3.8	5.3
Customer accounts receivable | Billed | Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer accounts receivable	0.0	0.0
Customer accounts receivable | Billed | Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer accounts receivable	0.9	3.3
Customer accounts receivable | Unbilled
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer accounts receivable	62.2	110.0
Customer accounts receivable | Unbilled | Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer accounts receivable	17.0	50.7
Customer accounts receivable | Unbilled | Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer accounts receivable	$ 20.5	$ 27.9