SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash paid for (received from):
Interest, net of amount capitalized	$ 500.9	$ 393.7	$ 356.9
Income taxes, net of refunds	34.4	21.6	(19.6)
Non-cash investing transactions:
Property, plant and equipment additions (reductions)	251.3	354.7	269.3
Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.0	0.0	0.2
Evergy Kansas Central
Cash paid for (received from):
Interest, net of amount capitalized	195.3	170.2	149.3
Income taxes, net of refunds	54.4	79.8	37.5
Non-cash investing transactions:
Property, plant and equipment additions (reductions)	134.1	203.9	101.9
Evergy Kansas Central | Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.0	0.0	0.2
Evergy Metro
Cash paid for (received from):
Interest, net of amount capitalized	134.3	114.6	110.8
Income taxes, net of refunds	9.8	(15.2)	36.6
Non-cash investing transactions:
Property, plant and equipment additions (reductions)	$ 83.2	$ 125.8	$ 102.2