ASSET RETIREMENT OBLIGATIONS - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Increase to ARO to decommission Wolf Creek resulting from study	$ 259.1
Evergy Kansas Central
Jointly Owned Utility Plant Interests [Line Items]
Increase to ARO to decommission Wolf Creek resulting from study	140.7
Evergy Metro
Jointly Owned Utility Plant Interests [Line Items]
Increase to ARO to decommission Wolf Creek resulting from study	$ 118.4