PENSION PLANS AND POST-RETIREMENT BENEFITS PENSION PLANS AND POST-RETIREMENT BENEFITS - Schedule of Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 20.0	$ 21.2	$ 39.9	$ 42.3
Interest cost	19.8	21.3	39.6	42.6
Expected return on plan assets	(26.0)	(26.8)	(52.0)	(53.6)
Prior service cost	0.4	0.5	0.9	1.0
Recognized net actuarial (gain) loss	8.8	14.7	17.5	29.5
Net periodic benefit costs before regulatory adjustment and intercompany allocations	23.0	30.9	45.9	61.8
Regulatory adjustment	15.0	6.6	30.9	13.7
Intercompany allocations	0.0	0.0	0.0	0.0
Net periodic benefit costs (income)	38.0	37.5	76.8	75.5
Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.7	0.9	1.5	1.7
Interest cost	2.0	1.9	4.0	3.9
Expected return on plan assets	(2.6)	(2.2)	(5.1)	(4.4)
Prior service cost	0.1	0.2	0.2	0.3
Recognized net actuarial (gain) loss	0.0	0.3	(0.1)	0.6
Net periodic benefit costs before regulatory adjustment and intercompany allocations	0.2	1.1	0.5	2.1
Regulatory adjustment	(0.6)	(1.3)	(1.2)	(2.5)
Intercompany allocations	0.0	0.0	0.0	0.0
Net periodic benefit costs (income)	(0.4)	(0.2)	(0.7)	(0.4)
Evergy Kansas Central | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	7.7	7.5	15.4	14.9
Interest cost	9.7	10.4	19.4	20.7
Expected return on plan assets	(12.8)	(13.5)	(25.6)	(27.1)
Prior service cost	0.5	0.5	1.0	1.0
Recognized net actuarial (gain) loss	6.4	9.5	12.8	19.3
Net periodic benefit costs before regulatory adjustment and intercompany allocations	11.5	14.4	23.0	28.8
Regulatory adjustment	2.8	0.1	5.7	(0.8)
Intercompany allocations	(0.1)	0.8	0.4	1.2
Net periodic benefit costs (income)	14.2	15.3	29.1	29.2
Evergy Kansas Central | Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.4	0.4	0.8	0.8
Interest cost	1.0	1.0	2.0	2.0
Expected return on plan assets	(1.6)	(1.5)	(3.2)	(3.1)
Prior service cost	0.1	0.1	0.2	0.2
Recognized net actuarial (gain) loss	0.0	0.1	(0.1)	0.3
Net periodic benefit costs before regulatory adjustment and intercompany allocations	(0.1)	0.1	(0.3)	0.2
Regulatory adjustment	(0.7)	(0.8)	(1.4)	(1.6)
Intercompany allocations	0.0	0.0	0.1	0.0
Net periodic benefit costs (income)	(0.8)	(0.7)	(1.6)	(1.4)
Evergy Metro | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	12.3	13.7	24.5	27.4
Interest cost	10.0	10.8	19.9	21.6
Expected return on plan assets	(14.1)	(14.4)	(28.2)	(28.9)
Prior service cost	0.0	0.0	0.0	0.0
Recognized net actuarial (gain) loss	9.6	11.1	19.3	22.3
Net periodic benefit costs before regulatory adjustment and intercompany allocations	17.8	21.2	35.5	42.4
Regulatory adjustment	5.7	1.6	12.2	4.6
Intercompany allocations	(3.9)	(6.3)	(8.4)	(12.2)
Net periodic benefit costs (income)	19.6	16.5	39.3	34.8
Evergy Metro | Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.3	0.5	0.7	0.9
Interest cost	0.9	0.9	1.9	1.9
Expected return on plan assets	(1.0)	(0.6)	(1.9)	(1.3)
Prior service cost	(0.3)	(0.2)	(0.7)	(0.5)
Recognized net actuarial (gain) loss	0.0	(0.1)	(0.2)	(0.1)
Net periodic benefit costs before regulatory adjustment and intercompany allocations	(0.1)	0.5	(0.2)	0.9
Regulatory adjustment	0.7	0.0	1.3	0.1
Intercompany allocations	(0.2)	(0.1)	(0.3)	(0.2)
Net periodic benefit costs (income)	$ 0.4	$ 0.4	$ 0.8	$ 0.8