Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for uncollectible accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning Of Period	$ 9.2	$ 6.7	$ 6.7
Additions Charged To Costs And Expenses	27.2	20.7	10.5
Additions Charged To Other Accounts	12.4	16.9	7.0
Deductions	38.3	35.1	17.5
Balance At End Of Period	10.5	9.2	6.7
Allowance for uncollectible accounts | Evergy Kansas Central
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning Of Period	3.9	6.7	6.7
Additions Charged To Costs And Expenses	7.2	9.0	10.5
Additions Charged To Other Accounts	3.4	7.4	7.0
Deductions	10.7	19.2	17.5
Balance At End Of Period	3.8	3.9	6.7
Allowance for uncollectible accounts | Evergy Metro
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning Of Period	3.8	2.2	1.8
Additions Charged To Costs And Expenses	13.7	13.1	7.5
Additions Charged To Other Accounts	6.3	4.4	5.6
Deductions	19.2	15.9	12.7
Balance At End Of Period	4.6	3.8	2.2
Tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning Of Period	27.3	0.0
Additions Charged To Costs And Expenses	0.6	2.2
Additions Charged To Other Accounts	0.0	26.8
Deductions	10.4	1.7
Balance At End Of Period	17.5	27.3	0.0
Tax valuation allowance | Evergy Kansas Central
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning Of Period	1.7	0.0
Additions Charged To Costs And Expenses	0.0	1.7
Additions Charged To Other Accounts	0.0	0.0
Deductions	1.7	0.0
Balance At End Of Period	$ 0.0	1.7	0.0
Tax valuation allowance | Evergy Metro
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning Of Period		$ 0.0	0.0
Additions Charged To Costs And Expenses			1.2
Additions Charged To Other Accounts			0.0
Deductions			1.2
Balance At End Of Period			$ 0.0