ORGANIZATION AND BASIS OF PRESENTATION - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income
Net income	$ 72.2	$ 103.4
Less: Net income attributable to noncontrolling interests	2.8	3.9
Net income attributable to Evergy, Inc.	$ 69.4	$ 99.5
Common Shares Outstanding
Weighted average equivalent common shares outstanding - basic (in shares)	227.1	252.8
Add: effect of dilutive securities (in shares)	0.4	0.2
Diluted average number of common shares outstanding (in shares)	227.5	253.0
Basic and diluted earnings per common share (in dollars per share)	$ 0.31	$ 0.39