LEASES - Schedule of Future Payments for Finance Leases (Details) $ in Millions	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
2021	$ 8.8
2022	7.3
2023	6.6
2024	5.3
2025	4.6
After 2025	42.4
Total finance lease payments	75.0
Amounts representing imputed interest	(23.7)
Present value of lease payments	51.3
Less: current portion	(6.0)
Total long-term obligations under finance leases	45.3
Right-of-use assets under finance leases included in property, plant and equipment, net on the consolidated balance sheets	$ 314.1
Weighted-average remaining lease term (years)	13 years 6 months
Weighted-average discount rate	5.60%
Evergy Kansas Central
Lessee, Lease, Description [Line Items]
2021	$ 8.0
2022	6.5
2023	5.8
2024	4.6
2025	4.1
After 2025	41.2
Total finance lease payments	70.2
Amounts representing imputed interest	(22.7)
Present value of lease payments	47.5
Less: current portion	(5.6)
Total long-term obligations under finance leases	41.9
Right-of-use assets under finance leases included in property, plant and equipment, net on the consolidated balance sheets	$ 53.9
Weighted-average remaining lease term (years)	14 years 1 month 6 days
Weighted-average discount rate	5.50%
Evergy Metro
Lessee, Lease, Description [Line Items]
2021	$ 0.6
2022	0.6
2023	0.6
2024	0.6
2025	0.2
After 2025	0.6
Total finance lease payments	3.2
Amounts representing imputed interest	(0.6)
Present value of lease payments	2.6
Less: current portion	(0.4)
Total long-term obligations under finance leases	2.2
Right-of-use assets under finance leases included in property, plant and equipment, net on the consolidated balance sheets	$ 2.6
Weighted-average remaining lease term (years)	5 years 10 months 24 days
Weighted-average discount rate	4.90%