VARIABLE INTEREST ENTITIES - Assets and Liabilities Related to VIE (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets:
Property, plant and equipment of variable interest entities, net	$ 19,951.0	$ 19,184.4
Liabilities:
Current maturities of long-term debt of variable interest entities	436.4	251.1
Accrued interest	123.4	122.3
Long-term debt, net	9,190.9	8,746.7
Variable Interest Entities
Assets:
Property, plant and equipment of variable interest entities, net	154.9	162.0
Liabilities:
Current maturities of long-term debt of variable interest entities	18.8	32.3
Accrued interest	0.1	0.3
Long-term debt, net	0.0	18.8
Evergy Kansas Central
Assets:
Property, plant and equipment of variable interest entities, net	10,193.6	9,864.9
Liabilities:
Current maturities of long-term debt of variable interest entities	0.0	250.0
Accrued interest	72.8	74.2
Long-term debt, net	3,931.5	3,436.1
Evergy Kansas Central | Variable Interest Entities
Assets:
Property, plant and equipment of variable interest entities, net	154.9	162.0
Liabilities:
Current maturities of long-term debt of variable interest entities	18.8	32.3
Long-term debt, net	$ 0.0	$ 18.8