REVENUE (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 1,085.9	$ 1,185.1
Other	30.8	31.8
Operating revenues	1,116.7	1,216.9
Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	542.2	592.3
Other	17.9	4.5
Operating revenues	560.1	596.8
Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	363.4	402.9
Other	12.1	22.5
Operating revenues	375.5	425.4
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	402.5	451.7
Residential | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	167.8	192.3
Residential | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	147.4	164.2
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	384.7	413.5
Commercial | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	151.1	164.3
Commercial | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	172.1	183.8
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	140.6	147.0
Industrial | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	92.1	98.4
Industrial | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	30.1	29.7
Other retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	10.6	9.8
Other retail | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4.7	5.1
Other retail | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3.5	2.6
Total electric retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	938.4	1,022.0
Total electric retail | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	415.7	460.1
Total electric retail | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	353.1	380.3
Wholesale
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	63.5	83.1
Wholesale | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	54.8	61.3
Wholesale | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6.8	18.1
Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	75.6	76.7
Transmission | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	68.2	69.2
Transmission | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3.1	3.1
Industrial steam and other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8.4	3.3
Industrial steam and other | Evergy Kansas Central
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3.5	1.7
Industrial steam and other | Evergy Metro
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 0.4	$ 1.4