RECEIVABLES - Allowance for Credit Loses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 10.5	$ 9.2
Credit loss expense	2.7	3.8
Write-offs	(5.0)	(6.5)
Recoveries of prior write-offs	3.3	3.3
Ending balance	11.5	9.8
Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	3.8	3.9
Credit loss expense	0.8	(0.5)
Write-offs	(1.2)	(0.2)
Recoveries of prior write-offs	0.7	1.0
Ending balance	4.1	4.2
Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	4.6	3.8
Credit loss expense	1.4	2.8
Write-offs	(2.6)	(4.2)
Recoveries of prior write-offs	1.8	1.6
Ending balance	$ 5.2	$ 4.0