PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Electric plant in service	$ 28,914.8	$ 27,768.8
Electric plant acquisition adjustment	724.3	740.6
Accumulated depreciation	(10,998.4)	(10,293.7)
Plant in service	18,640.7	18,215.7
Construction work in progress	1,153.5	839.2
Nuclear fuel, net	155.9	128.5
Plant to be retired, net	0.9	1.0
Property, plant and equipment, net	19,951.0	19,184.4
Variable Interest Entities
Property, Plant and Equipment [Line Items]
Electric plant in service	392.1	392.1
Accumulated depreciation	(237.2)	(230.1)
Property, plant and equipment, net	154.9	162.0
Evergy Kansas Central
Property, Plant and Equipment [Line Items]
Electric plant in service	14,095.1	13,538.1
Electric plant acquisition adjustment	724.3	740.6
Accumulated depreciation	(5,293.5)	(4,951.5)
Plant in service	9,525.9	9,327.2
Construction work in progress	589.1	472.8
Nuclear fuel, net	77.7	63.9
Plant to be retired, net	0.9	1.0
Property, plant and equipment, net	10,193.6	9,864.9
Evergy Kansas Central | Variable Interest Entities
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	154.9	162.0
Evergy Metro
Property, Plant and Equipment [Line Items]
Electric plant in service	11,161.8	10,776.5
Electric plant acquisition adjustment	0.0	0.0
Accumulated depreciation	(4,532.7)	(4,272.0)
Plant in service	6,629.1	6,504.5
Construction work in progress	433.9	269.9
Nuclear fuel, net	78.2	64.6
Plant to be retired, net	0.0	0.0
Property, plant and equipment, net	$ 7,141.2	$ 6,839.0