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FAIR VALUE MEASUREMENTS - Recurring (Details) - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Assets    
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Other assets, Other Other assets, Other
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Other, Other Other, Other
Fair Value, Measurements, Recurring    
Assets    
Total nuclear decommissioning trust $ 766.4 $ 653.3
Total rabbi trust 33.3 34.1
Derivative Asset 42.7 50.3
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (90.3) (279.5)
Total self-insured health plan trust 15.7 11.2
Total Assets 858.1 748.9
Derivative Liability 45.4 52.5
FIN 39 Derivative liability netting (83.4) (270.4)
Total Liabilities 45.4 52.5
Fair Value, Measurements, Recurring | Level 1    
Assets    
Total nuclear decommissioning trust 653.7 547.1
Total rabbi trust 33.3 34.1
Derivative Asset, Fair Value, Gross Asset 89.0 268.0
Total self-insured health plan trust 8.8 5.7
Total Assets 784.8 854.9
Derivative Liability, Fair Value, Gross Liability 82.0 250.8
Total Liabilities 82.0 250.8
Fair Value, Measurements, Recurring | Level 2    
Assets    
Total nuclear decommissioning trust 47.8 43.4
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 33.6 46.6
Total self-insured health plan trust 6.9 5.5
Total Assets 88.3 95.5
Derivative Liability, Fair Value, Gross Liability 36.9 59.7
Total Liabilities 36.9 59.7
Fair Value, Measurements, Recurring | Level 3    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 10.4 15.2
Total self-insured health plan trust 0.0 0.0
Total Assets 10.4 15.2
Derivative Liability, Fair Value, Gross Liability 9.9 12.4
Total Liabilities 9.9 12.4
Fair Value, Measurements, Recurring | NAV    
Assets    
Total nuclear decommissioning trust 64.9 62.8
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total self-insured health plan trust 0.0 0.0
Total Assets 64.9 62.8
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Total Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | Power commodity contract    
Assets    
Derivative Asset 42.0 43.0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (16.9) (64.2)
Derivative Liability 43.9 47.4
FIN 39 Derivative liability netting (10.0) (55.1)
Fair Value, Measurements, Recurring | Power commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 16.3 45.5
Derivative Liability, Fair Value, Gross Liability 9.4 34.2
Fair Value, Measurements, Recurring | Power commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 32.2 46.5
Derivative Liability, Fair Value, Gross Liability 34.6 55.9
Fair Value, Measurements, Recurring | Power commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 10.4 15.2
Derivative Liability, Fair Value, Gross Liability 9.9 12.4
Fair Value, Measurements, Recurring | Power commodity contract | NAV    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Fair Value, Measurements, Recurring | Natural gas commodity contract    
Assets    
Derivative Asset 0.7 7.3
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (73.4) (215.3)
Derivative Liability 1.5 5.1
FIN 39 Derivative liability netting (73.4) (215.3)
Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 72.7 222.5
Derivative Liability, Fair Value, Gross Liability 72.6 216.6
Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 1.4 0.1
Derivative Liability, Fair Value, Gross Liability 2.3 3.8
Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Fair Value, Measurements, Recurring | Natural gas commodity contract | NAV    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability $ 0.0 $ 0.0
Evergy Kansas Central    
Assets    
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Other assets, Other Other assets, Other
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Other, Other Other, Other
Evergy Kansas Central | Fair Value, Measurements, Recurring    
Assets    
Total nuclear decommissioning trust $ 365.1 $ 318.8
Total rabbi trust 24.5 24.9
Derivative Asset 40.9 49.9
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (87.2) (275.0)
Total Assets 430.5 393.6
Derivative Liability 40.7 48.0
FIN 39 Derivative liability netting (80.3) (265.8)
Total Liabilities 40.7 48.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Core bond fund    
Assets    
Total nuclear decommissioning trust 56.2 51.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 29.1 25.3
Evergy Kansas Central | Fair Value, Measurements, Recurring | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 18.3 16.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Combination debt/equity/other fund    
Assets    
Total rabbi trust 1.7 1.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Alternative investments fund    
Assets    
Total nuclear decommissioning trust 37.9 31.8
Evergy Kansas Central | Fair Value, Measurements, Recurring | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 17.2 18.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.7 0.4
Total rabbi trust 0.2 0.1
Evergy Kansas Central | Fair Value, Measurements, Recurring | Equity funds    
Assets    
Total rabbi trust 7.4 7.3
Evergy Kansas Central | Fair Value, Measurements, Recurring | Fixed income funds    
Assets    
Total rabbi trust 15.2 15.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1    
Assets    
Total nuclear decommissioning trust 300.2 256.0
Total rabbi trust 24.5 24.9
Derivative Asset, Fair Value, Gross Asset 89.0 268.0
Total Assets 413.7 548.9
Derivative Liability, Fair Value, Gross Liability 82.0 250.6
Total Liabilities 82.0 250.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Core bond fund    
Assets    
Total nuclear decommissioning trust 56.2 51.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 29.1 25.3
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 18.3 16.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Combination debt/equity/other fund    
Assets    
Total rabbi trust 1.7 1.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Alternative investments fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.7 0.4
Total rabbi trust 0.2 0.1
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Equity funds    
Assets    
Total rabbi trust 7.4 7.3
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Fixed income funds    
Assets    
Total rabbi trust 15.2 15.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 33.6 46.6
Total Assets 33.6 46.6
Derivative Liability, Fair Value, Gross Liability 35.8 56.0
Total Liabilities 35.8 56.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Core bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Combination debt/equity/other fund    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Alternative investments fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Equity funds    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 2 | Fixed income funds    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 5.5 10.3
Total Assets 5.5 10.3
Derivative Liability, Fair Value, Gross Liability 3.2 7.2
Total Liabilities 3.2 7.2
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Core bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Combination debt/equity/other fund    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Alternative investments fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Equity funds    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 3 | Fixed income funds    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV    
Assets    
Total nuclear decommissioning trust 64.9 62.8
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total Assets 64.9 62.8
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Total Liabilities 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Core bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Combination debt/equity/other fund    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Alternative investments fund    
Assets    
Total nuclear decommissioning trust 37.9 31.8
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 17.2 18.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Equity funds    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Fixed income funds    
Assets    
Total rabbi trust 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract    
Assets    
Derivative Asset 40.2 42.6
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (13.8) (59.7)
Derivative Liability 40.3 46.6
FIN 39 Derivative liability netting (6.9) (50.5)
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 16.3 45.5
Derivative Liability, Fair Value, Gross Liability 9.4 34.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 32.2 46.5
Derivative Liability, Fair Value, Gross Liability 34.6 55.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 5.5 10.3
Derivative Liability, Fair Value, Gross Liability 3.2 7.2
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | NAV    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract    
Assets    
Derivative Asset 0.7 7.3
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (73.4) (215.3)
Derivative Liability 0.4 1.4
FIN 39 Derivative liability netting (73.4) (215.3)
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 72.7 222.5
Derivative Liability, Fair Value, Gross Liability 72.6 216.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 1.4 0.1
Derivative Liability, Fair Value, Gross Liability 1.2 0.1
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract | NAV    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Evergy Kansas Central | Domestic | Fair Value, Measurements, Recurring | Equity securities    
Assets    
Total nuclear decommissioning trust 133.1 112.5
Evergy Kansas Central | Domestic | Fair Value, Measurements, Recurring | Level 1 | Equity securities    
Assets    
Total nuclear decommissioning trust 123.3 100.4
Evergy Kansas Central | Domestic | Fair Value, Measurements, Recurring | Level 2 | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Domestic | Fair Value, Measurements, Recurring | Level 3 | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | Domestic | Fair Value, Measurements, Recurring | NAV | Equity securities    
Assets    
Total nuclear decommissioning trust 9.8 12.1
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | Equity securities    
Assets    
Total nuclear decommissioning trust 72.6 62.9
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | Level 1 | Equity securities    
Assets    
Total nuclear decommissioning trust 72.6 62.9
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | Level 2 | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | Level 3 | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | NAV | Equity securities    
Assets    
Total nuclear decommissioning trust $ 0.0 $ 0.0
Evergy Metro    
Assets    
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Other assets, Other Other assets, Other
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Other, Other Other, Other
Evergy Metro | Fair Value, Measurements, Recurring    
Assets    
Total nuclear decommissioning trust $ 401.3 $ 334.5
Derivative Asset 0.0 0.0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (2.1) (3.5)
Total self-insured health plan trust 15.7 11.2
Total Assets 417.0 345.7
Derivative Liability 3.6 0.6
FIN 39 Derivative liability netting (2.1) (3.5)
Total Liabilities 3.6 0.6
Evergy Metro | Fair Value, Measurements, Recurring | Equity securities    
Assets    
Total nuclear decommissioning trust 302.4 243.4
Total self-insured health plan trust 2.0 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Cash equivalents    
Assets    
Total nuclear decommissioning trust 3.2 6.6
Evergy Metro | Fair Value, Measurements, Recurring | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 47.9 40.7
Evergy Metro | Fair Value, Measurements, Recurring | U.S. Agency    
Assets    
Total nuclear decommissioning trust   0.4
Evergy Metro | Fair Value, Measurements, Recurring | State and local obligations    
Assets    
Total nuclear decommissioning trust 3.8 4.2
Evergy Metro | Fair Value, Measurements, Recurring | Corporate bonds    
Assets    
Total nuclear decommissioning trust 43.9 39.1
Evergy Metro | Fair Value, Measurements, Recurring | Foreign governments    
Assets    
Total nuclear decommissioning trust 0.1 0.1
Evergy Metro | Fair Value, Measurements, Recurring | Debt securities    
Assets    
Total self-insured health plan trust 9.4 8.0
Evergy Metro | Fair Value, Measurements, Recurring | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 4.3 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 1    
Assets    
Total nuclear decommissioning trust 353.5 291.1
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total self-insured health plan trust 8.8 5.7
Total Assets 362.3 296.8
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Total Liabilities 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Equity securities    
Assets    
Total nuclear decommissioning trust 302.4 243.4
Total self-insured health plan trust 2.0 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 3.2 6.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 47.9 40.7
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | U.S. Agency    
Assets    
Total nuclear decommissioning trust   0.4
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | State and local obligations    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Corporate bonds    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Foreign governments    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Debt securities    
Assets    
Total self-insured health plan trust 2.5 2.5
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 4.3 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 2    
Assets    
Total nuclear decommissioning trust 47.8 43.4
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total self-insured health plan trust 6.9 5.5
Total Assets 54.7 48.9
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Total Liabilities 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | U.S. Agency    
Assets    
Total nuclear decommissioning trust   0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | State and local obligations    
Assets    
Total nuclear decommissioning trust 3.8 4.2
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Corporate bonds    
Assets    
Total nuclear decommissioning trust 43.9 39.1
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Foreign governments    
Assets    
Total nuclear decommissioning trust 0.1 0.1
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Debt securities    
Assets    
Total self-insured health plan trust 6.9 5.5
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 2.1 3.5
Total self-insured health plan trust 0.0 0.0
Total Assets 2.1 3.5
Derivative Liability, Fair Value, Gross Liability 5.7 4.1
Total Liabilities 5.7 4.1
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | U.S. Agency    
Assets    
Total nuclear decommissioning trust   0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | State and local obligations    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | Corporate bonds    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | Foreign governments    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | Debt securities    
Assets    
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Level 3 | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total self-insured health plan trust 0.0 0.0
Total Assets 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Total Liabilities 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | Equity securities    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | U.S. Agency    
Assets    
Total nuclear decommissioning trust   0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | State and local obligations    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | Corporate bonds    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | Foreign governments    
Assets    
Total nuclear decommissioning trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | Debt securities    
Assets    
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | NAV | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Power commodity contract    
Assets    
Derivative Asset 0.0 0.0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (2.1) (3.5)
Derivative Liability 3.6 0.6
FIN 39 Derivative liability netting (2.1) (3.5)
Evergy Metro | Fair Value, Measurements, Recurring | Power commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Power commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Evergy Metro | Fair Value, Measurements, Recurring | Power commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 2.1 3.5
Derivative Liability, Fair Value, Gross Liability 5.7 4.1
Evergy Metro | Fair Value, Measurements, Recurring | Power commodity contract | NAV    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability $ 0.0 $ 0.0
Other Evergy    
Assets    
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Other assets, Other Other assets, Other
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Other, Other Other, Other
Other Evergy | Fair Value, Measurements, Recurring    
Assets    
Total rabbi trust $ 8.8 $ 9.2
Derivative Asset 1.8 0.4
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (1.0) (1.0)
Total Assets 10.6 9.6
Derivative Liability 1.1 3.9
FIN 39 Derivative liability netting (1.0) (1.1)
Total Liabilities 1.1 3.9
Other Evergy | Fair Value, Measurements, Recurring | Core bond fund    
Assets    
Total rabbi trust 8.8 9.2
Other Evergy | Fair Value, Measurements, Recurring | Level 1    
Assets    
Total rabbi trust 8.8 9.2
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total Assets 8.8 9.2
Derivative Liability, Fair Value, Gross Liability 0.0 0.2
Total Liabilities 0.0 0.2
Other Evergy | Fair Value, Measurements, Recurring | Level 1 | Core bond fund    
Assets    
Total rabbi trust 8.8 9.2
Other Evergy | Fair Value, Measurements, Recurring | Level 2    
Assets    
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total Assets 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 1.1 3.7
Total Liabilities 1.1 3.7
Other Evergy | Fair Value, Measurements, Recurring | Level 2 | Core bond fund    
Assets    
Total rabbi trust 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Level 3    
Assets    
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 2.8 1.4
Total Assets 2.8 1.4
Derivative Liability, Fair Value, Gross Liability 1.0 1.1
Total Liabilities 1.0 1.1
Other Evergy | Fair Value, Measurements, Recurring | Level 3 | Core bond fund    
Assets    
Total rabbi trust 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | NAV    
Assets    
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total Assets 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Total Liabilities 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | NAV | Core bond fund    
Assets    
Total rabbi trust 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Power commodity contract    
Assets    
Derivative Asset 1.8 0.4
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (1.0) (1.0)
Derivative Liability 0.0 0.2
FIN 39 Derivative liability netting (1.0) (1.1)
Other Evergy | Fair Value, Measurements, Recurring | Power commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.2
Other Evergy | Fair Value, Measurements, Recurring | Power commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Power commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 2.8 1.4
Derivative Liability, Fair Value, Gross Liability 1.0 1.1
Other Evergy | Fair Value, Measurements, Recurring | Power commodity contract | NAV    
Assets    
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Natural gas commodity contract    
Assets    
Derivative Liability 1.1 3.7
FIN 39 Derivative liability netting 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 1    
Assets    
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 2    
Assets    
Derivative Liability, Fair Value, Gross Liability 1.1 3.7
Other Evergy | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 3    
Assets    
Derivative Liability, Fair Value, Gross Liability 0.0 0.0
Other Evergy | Fair Value, Measurements, Recurring | Natural gas commodity contract | NAV    
Assets    
Derivative Liability, Fair Value, Gross Liability $ 0.0 $ 0.0