QUARTERLY OPERATING RESULTS (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating revenue	$ 1,131.6	$ 1,577.6	$ 1,221.7	$ 1,216.9	$ 1,199.8	$ 1,582.5	$ 893.4	$ 600.2	$ 5,147.8	$ 4,275.9	$ 2,571.0
Operating income	165.8	538.7	271.7	209.6	150.1	533.1	126.9	123.5	1,185.8	933.6	678.8
Net income (loss)	66.7	370.9	144.6	103.4	21.1	357.6	104.4	62.9	685.6	546.0	336.5
Net income	$ 63.9	$ 366.8	$ 139.7	$ 99.5	$ 18.5	$ 355.0	$ 101.8	$ 60.5	669.9	535.8	323.9
Basic and diluted earnings per common share (in dollars per share)	$ 0.28	$ 1.56	$ 0.57	$ 0.39	$ 0.07	$ 1.32	$ 0.56	$ 0.42
Evergy Kansas Central
Operating revenue	$ 576.1	$ 749.0	$ 585.5	$ 596.8	$ 599.0	$ 764.8	$ 650.9	$ 600.2	2,507.4	2,614.9	2,571.0
Operating income	102.2	242.4	127.6	124.3	94.0	256.9	76.1	123.5	596.5	550.5	678.8
Net income (loss)	55.4	168.2	67.2	68.3	30.6	178.0	77.6	62.9	359.1	349.1	336.5
Net income	52.6	164.1	62.3	64.4	28.0	175.4	75.0	60.5	343.4	338.9	323.9
Evergy Metro
Operating revenue	375.3	568.8	437.0	425.4	414.2	559.6	452.2	397.1	1,806.5	1,823.1	1,890.7
Operating income	52.2	215.5	101.9	56.9	44.7	189.4	114.7	61.0	426.5	409.8	486.4
Net income (loss)	$ 27.9	$ 151.9	$ 59.4	$ 16.0	$ (2.2)	$ 120.3	$ 24.6	$ 20.2	255.2	162.9	179.8
Net income									$ 255.2	$ 162.9	$ 179.8