ORGANIZATION AND BASIS OF PRESENTATION - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Income
Net income	$ 431.2	$ 197.6	$ 125.6	$ 452.5	$ 188.3	$ 194.6	$ 754.4	$ 835.4
Less: Net income attributable to noncontrolling interests	3.0			3.1			9.2	9.1
Net income attributable to Evergy, Inc.	$ 428.2			$ 449.4			$ 745.2	$ 826.3
Common Shares Outstanding
Weighted average equivalent common shares outstanding - basic (in shares)	229.9			229.7			229.9	228.8
Add: effect of dilutive securities (in shares)	0.7			0.5			0.6	0.5
Diluted average number of common shares outstanding (in shares)	230.6			230.2			230.5	229.3
Earnings Per Share, Basic	$ 1.86			$ 1.96			$ 3.24	$ 3.61
Earnings Per Share, Diluted	$ 1.86			$ 1.95			$ 3.23	$ 3.60