ORGANIZATION AND BASIS OF PRESENTATION - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash paid for (received from):
Interest, net of amount capitalized	$ 185.3	$ 173.9
Income taxes, net of refunds	0.2	(17.7)
Right-of-use assets obtained in exchange for new operating lease liabilities	3.8	2.2
Non-cash investing transactions:
Property, plant and equipment additions	113.2	93.1
Non-cash financing transactions:
Issuance of stock for compensation and reinvested dividends	0.9	(0.3)
Right-of-use assets obtained in exchange for new finance lease liabilities	3.5	2.3
Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.6	1.0
Evergy Kansas Central
Cash paid for (received from):
Interest, net of amount capitalized	82.7	76.9
Income taxes, net of refunds	0.2	(10.4)
Right-of-use assets obtained in exchange for new operating lease liabilities	3.5	0.0
Non-cash investing transactions:
Property, plant and equipment additions	46.3	24.2
Non-cash financing transactions:
Right-of-use assets obtained in exchange for new finance lease liabilities	2.2	2.3
Evergy Kansas Central | Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.6	1.0
Evergy Metro
Cash paid for (received from):
Interest, net of amount capitalized	54.9	64.6
Income taxes, net of refunds	0.0	17.5
Right-of-use assets obtained in exchange for new operating lease liabilities	0.3	2.2
Non-cash investing transactions:
Property, plant and equipment additions	46.4	64.5
Non-cash financing transactions:
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 1.3	$ 0.0