ORGANIZATION AND BASIS OF PRESENTATION - Other Income And Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Entity Information [Line Items]
Non-service cost component of net benefit cost	$ (16.2)	$ (13.1)
Other	(6.5)	(6.3)
Other expense	(22.7)	(19.4)
Evergy Kansas Central
Entity Information [Line Items]
Non-service cost component of net benefit cost	(5.6)	(4.4)
Other	(5.9)	(6.2)
Other expense	(11.5)	(10.6)
Evergy Metro
Entity Information [Line Items]
Non-service cost component of net benefit cost	(6.9)	(5.1)
Other	(0.5)	0.1
Other expense	$ (7.4)	$ (5.0)