ORGANIZATION AND BASIS OF PRESENTATION - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash paid for (received from):
Interest, net of amount capitalized	$ 78.6	$ 86.5
Income taxes, net of refunds	2.6	0.2
Right-of-use assets obtained in exchange for new operating lease liabilities	2.2	2.6
Right-of-use assets obtained in exchange for new finance lease liabilities	0.2	3.1
Non-cash investing transactions:
Property, plant and equipment additions	104.4	75.7
Non-cash financing transactions:
Issuance of stock for compensation and reinvested dividends	0.7	0.9
Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.2	0.6
Evergy Kansas Central
Cash paid for (received from):
Interest, net of amount capitalized	31.2	37.4
Income taxes, net of refunds	2.6	0.2
Right-of-use assets obtained in exchange for new operating lease liabilities	1.5	2.6
Right-of-use assets obtained in exchange for new finance lease liabilities	0.2	1.9
Non-cash investing transactions:
Property, plant and equipment additions	45.4	52.5
Evergy Kansas Central | Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.2	0.6
Evergy Metro
Cash paid for (received from):
Interest, net of amount capitalized	18.6	18.7
Income taxes, net of refunds	(1.6)	0.0
Right-of-use assets obtained in exchange for new operating lease liabilities	0.7	0.0
Right-of-use assets obtained in exchange for new finance lease liabilities	0.0	1.2
Non-cash investing transactions:
Property, plant and equipment additions	$ 34.6	$ 17.8