SHORT-TERM BORROWINGS AND SHORT-TERM BANK LINES OF CREDIT - Narrative (Details) - Cash Borrowings	Mar. 31, 2020 USD ($)
Short-term Debt [Line Items]
Line of credit, maximum borrowing capacity	$ 2,500,000,000
Debt instrument, debt default, threshold	$ 100,000,000.0
Debt Instrument, debt to capitalization ratio (no more than)	65.00%
Evergy Kansas Central
Short-term Debt [Line Items]
Debt instrument, debt default, threshold	$ 100,000,000.0
Debt Instrument, debt to capitalization ratio (no more than)	65.00%
Evergy Metro
Short-term Debt [Line Items]
Debt instrument, debt default, threshold	$ 100,000,000.0
Debt Instrument, debt to capitalization ratio (no more than)	65.00%
Evergy Missouri West Inc
Short-term Debt [Line Items]
Debt instrument, debt default, threshold	$ 100,000,000.0
Debt Instrument, debt to capitalization ratio (no more than)	65.00%