ORGANIZATION AND BASIS OF PRESENTATION - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 23,141.4	$ 22,136.5
Electric plant in service
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	33,693.3	32,129.3
Property, plant and equipment, adjustment	724.9	724.3
Accumulated depreciation	(12,856.9)	(12,304.9)
Property, plant and equipment, net	21,561.3	20,548.7
Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	1,403.6	1,421.2
Nuclear fuel, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	175.7	165.8
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	11,741.5	11,080.8
Evergy Kansas Central | Electric plant in service
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	16,236.7	15,376.9
Property, plant and equipment, adjustment	724.9	724.3
Accumulated depreciation	(6,157.1)	(5,922.9)
Property, plant and equipment, net	10,804.5	10,178.3
Evergy Kansas Central | Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	848.9	819.5
Evergy Kansas Central | Nuclear fuel, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	87.3	82.2
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	8,019.9	7,844.2
Evergy Metro | Electric plant in service
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,879.4	12,343.3
Property, plant and equipment, adjustment	0.0	0.0
Accumulated depreciation	(5,325.7)	(5,065.3)
Property, plant and equipment, net	7,553.7	7,278.0
Evergy Metro | Construction work in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	377.8	482.6
Evergy Metro | Nuclear fuel, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	88.4	83.6
Evergy Metro | Plant to be retired, net
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 0.0	$ 0.0