QUARTERLY OPERATING RESULTS (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating revenue	$ 1,094.4	$ 1,517.6	$ 1,184.7	$ 1,116.7	$ 1,131.6	$ 1,577.6	$ 1,221.7	$ 1,216.9	$ 4,913.4	$ 5,147.8	$ 4,275.9
Operating Income	153.0	521.7	271.7	197.5	165.8	538.7	271.7	209.6	1,143.9	1,185.8	933.6
Net income	54.0	367.5	136.3	72.2	66.7	370.9	144.6	103.4	630.0	685.6	546.0
Net income attributable to Evergy, Inc.	$ 51.0	$ 364.5	$ 133.4	$ 69.4	$ 63.9	$ 366.8	$ 139.7	$ 99.5	618.3	669.9	535.8
Basic and diluted earnings per common share (in dollars per share)	$ 0.22	$ 1.60	$ 0.59	$ 0.31	$ 0.28	$ 1.56	$ 0.57	$ 0.39
Evergy Kansas Central
Operating revenue	$ 553.6	$ 733.6	$ 570.8	$ 560.1	$ 576.1	$ 749.0	$ 585.5	$ 596.8	2,418.1	2,507.4	2,614.9
Operating Income	90.9	240.7	121.2	114.5	102.2	242.4	127.6	124.3	567.3	596.5	550.5
Net income	45.1	173.1	(37.6)	55.2	55.4	168.2	67.2	68.3	235.8	359.1	349.1
Net income attributable to Evergy, Inc.	42.1	170.1	(40.5)	52.4	52.6	164.1	62.3	64.4	224.1	343.4	338.9
Evergy Metro
Operating revenue	377.3	528.5	424.3	375.5	375.3	568.8	437.0	425.4	1,705.6	1,806.5	1,823.1
Operating Income	53.7	204.4	112.5	63.7	52.2	215.5	101.9	56.9	434.3	426.5	409.8
Net income	$ 22.5	$ 147.7	$ 102.9	$ 25.6	$ 27.9	$ 151.9	$ 59.4	$ 16.0	298.7	255.2	162.9
Net income attributable to Evergy, Inc.									$ 298.7	$ 255.2	$ 162.9