PENSION PLANS AND POST-RETIREMENT BENEFITS - Target Asset Allocations (Details)	Dec. 31, 2019
Evergy Kansas Central | Pension Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	29.00%
Evergy Kansas Central | Pension Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	20.00%
Evergy Kansas Central | Pension Benefits | Bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	36.00%
Evergy Kansas Central | Pension Benefits | Mortgage & asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Kansas Central | Pension Benefits | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	4.00%
Evergy Kansas Central | Pension Benefits | Other investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	11.00%
Evergy Kansas Central | Post-Retirement Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	33.00%
Evergy Kansas Central | Post-Retirement Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	22.00%
Evergy Kansas Central | Post-Retirement Benefits | Bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	45.00%
Evergy Kansas Central | Post-Retirement Benefits | Mortgage & asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Kansas Central | Post-Retirement Benefits | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Kansas Central | Post-Retirement Benefits | Other investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Metro Inc | Pension Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	31.00%
Evergy Metro Inc | Pension Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	21.00%
Evergy Metro Inc | Pension Benefits | Bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	35.00%
Evergy Metro Inc | Pension Benefits | Mortgage & asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Metro Inc | Pension Benefits | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	6.00%
Evergy Metro Inc | Pension Benefits | Other investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	7.00%
Evergy Metro Inc | Post-Retirement Benefits | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	3.00%
Evergy Metro Inc | Post-Retirement Benefits | International equities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Metro Inc | Post-Retirement Benefits | Bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	85.00%
Evergy Metro Inc | Post-Retirement Benefits | Mortgage & asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	4.00%
Evergy Metro Inc | Post-Retirement Benefits | Real estate investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	0.00%
Evergy Metro Inc | Post-Retirement Benefits | Other investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets, target allocation, percentage	8.00%