RECEIVABLES - Summary of Bad Debt Expense (Details) - Allowance for uncollectible accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment losses recognized on receivables	$ 27.2	$ 20.7	$ 10.5
Customer Contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment losses recognized on receivables	27.3	20.2	10.3
Evergy Kansas Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment losses recognized on receivables	7.2	9.0	10.5
Evergy Kansas Central | Customer Contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment losses recognized on receivables	7.3	8.5	10.3
Evergy Metro
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment losses recognized on receivables	13.7	13.1	7.5
Evergy Metro | Customer Contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impairment losses recognized on receivables	$ 13.7	$ 13.1	$ 7.6