ORGANIZATION AND BASIS OF PRESENTATION - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 21,686.9	$ 21,002.6
Electric plant in service
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	31,548.4	30,289.9
Property, plant and equipment, adjustment	724.3	724.3
Accumulated depreciation	(12,082.2)	(11,515.5)
Property, plant and equipment, net	20,190.5	19,498.7
Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	1,328.3	1,350.6
Nuclear fuel, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	167.3	152.5
Plant to be retired, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	0.8	0.8
Evergy Kansas Central
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	10,823.6	10,548.9
Evergy Kansas Central | Electric plant in service
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	15,053.8	14,686.3
Property, plant and equipment, adjustment	724.3	724.3
Accumulated depreciation	(5,835.6)	(5,590.8)
Property, plant and equipment, net	9,942.5	9,819.8
Evergy Kansas Central | Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	797.4	652.2
Evergy Kansas Central | Nuclear fuel, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	82.9	76.1
Evergy Kansas Central | Plant to be retired, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	0.8	0.8
Evergy Metro
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	7,675.9	7,474.9
Evergy Metro | Electric plant in service
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,172.7	11,656.9
Property, plant and equipment, adjustment	0.0	0.0
Accumulated depreciation	(4,995.5)	(4,733.7)
Property, plant and equipment, net	7,177.2	6,923.2
Evergy Metro | Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	414.3	475.3
Evergy Metro | Nuclear fuel, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	84.4	76.4
Evergy Metro | Plant to be retired, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 0.0	$ 0.0