ORGANIZATION AND BASIS OF PRESENTATION - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash paid for (received from):
Interest, net of amount capitalized	$ 267.8	$ 240.8
Income taxes, net of refunds	(73.8)	(13.1)
Right-of-use assets obtained in exchange for new operating lease liabilities	4.1	3.0
Right-of-use assets obtained in exchange for new finance lease liabilities	5.0	2.3
Non-cash investing transactions:
Property, plant and equipment additions	371.0	99.4
Non-cash financing transactions:
Issuance of stock for compensation and reinvested dividends	0.9	(0.3)
Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.8	1.6
Evergy Kansas Central
Cash paid for (received from):
Interest, net of amount capitalized	114.1	109.4
Income taxes, net of refunds	(6.4)	1.8
Right-of-use assets obtained in exchange for new operating lease liabilities	3.8	0.6
Right-of-use assets obtained in exchange for new finance lease liabilities	3.7	2.3
Non-cash investing transactions:
Property, plant and equipment additions	183.8	35.3
Evergy Kansas Central | Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.8	1.6
Evergy Metro
Cash paid for (received from):
Interest, net of amount capitalized	73.3	83.5
Income taxes, net of refunds	(7.3)	32.8
Right-of-use assets obtained in exchange for new operating lease liabilities	0.3	2.4
Right-of-use assets obtained in exchange for new finance lease liabilities	1.3	0.0
Non-cash investing transactions:
Property, plant and equipment additions	$ 165.6	$ 60.8