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FAIR VALUE MEASUREMENTS - Recurring (Details) - USD ($)
$ in Millions
Mar. 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 $ 689.5 $ 653.3
Total rabbi trust 33.7 34.1
Derivative Asset 59.0 50.3
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (130.8) (279.5)
Total self-insured health plan trust 12.0 11.2
Total Assets 794.2 748.9
Derivative Liability 53.7 52.5
FIN 39 Derivative liability netting (122.5) (270.4)
Total Liabilities 53.7 52.5
Fair Value, Measurements, Recurring | Level 1    
Assets    
Total nuclear decommissioning trust 581.0 547.1
Total rabbi trust 33.7 34.1
Derivative Asset, Fair Value, Gross Asset 132.9 268.0
Total self-insured health plan trust 7.2 5.7
Total Assets 754.8 854.9
Derivative Liability, Fair Value, Gross Liability 118.1 250.8
Total Liabilities 118.1 250.8
Fair Value, Measurements, Recurring | Level 2    
Assets    
Total nuclear decommissioning trust 44.8 43.4
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 37.7 46.6
Total self-insured health plan trust 4.8 5.5
Total Assets 87.3 95.5
Derivative Liability, Fair Value, Gross Liability 45.2 59.7
Total Liabilities 45.2 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 19.2 15.2
Total self-insured health plan trust 0.0 0.0
Total Assets 19.2 15.2
Derivative Liability, Fair Value, Gross Liability 12.9 12.4
Total Liabilities 12.9 12.4
Fair Value, Measurements, Recurring | NAV    
Assets    
Total nuclear decommissioning trust 63.7 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 63.7 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 48.1 43.0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (28.6) (64.2)
Derivative Liability 47.7 47.4
FIN 39 Derivative liability netting (20.3) (55.1)
Fair Value, Measurements, Recurring | Power commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 21.0 45.5
Derivative Liability, Fair Value, Gross Liability 13.7 34.2
Fair Value, Measurements, Recurring | Power commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 36.5 46.5
Derivative Liability, Fair Value, Gross Liability 41.4 55.9
Fair Value, Measurements, Recurring | Power commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 19.2 15.2
Derivative Liability, Fair Value, Gross Liability 12.9 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 10.9 7.3
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (102.2) (215.3)
Derivative Liability 6.0 5.1
FIN 39 Derivative liability netting (102.2) (215.3)
Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 111.9 222.5
Derivative Liability, Fair Value, Gross Liability 104.4 216.6
Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 1.2 0.1
Derivative Liability, Fair Value, Gross Liability 3.8 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 $ 335.1 $ 318.8
Total rabbi trust 24.4 24.9
Derivative Asset 59.0 49.9
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (127.2) (275.0)
Total Assets 418.5 393.6
Derivative Liability 45.6 48.0
FIN 39 Derivative liability netting (118.9) (265.8)
Total Liabilities 45.6 48.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Core bond fund    
Assets    
Total nuclear decommissioning trust 52.9 51.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 26.1 25.3
Evergy Kansas Central | Fair Value, Measurements, Recurring | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 16.6 16.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Combination debt/equity/other fund    
Assets    
Total rabbi trust 1.8 1.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Alternative investments fund    
Assets    
Total nuclear decommissioning trust 33.5 31.8
Evergy Kansas Central | Fair Value, Measurements, Recurring | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 18.3 18.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Cash equivalents    
Assets    
Total nuclear decommissioning trust 0.4 0.4
Total rabbi trust 0.1 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 15.1 15.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1    
Assets    
Total nuclear decommissioning trust 271.4 256.0
Total rabbi trust 24.4 24.9
Derivative Asset, Fair Value, Gross Asset 132.9 268.0
Total Assets 428.7 548.9
Derivative Liability, Fair Value, Gross Liability 116.8 250.6
Total Liabilities 116.8 250.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Core bond fund    
Assets    
Total nuclear decommissioning trust 52.9 51.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | High-yield bond fund    
Assets    
Total nuclear decommissioning trust 26.1 25.3
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Emerging markets bond fund    
Assets    
Total nuclear decommissioning trust 16.6 16.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Level 1 | Combination debt/equity/other fund    
Assets    
Total rabbi trust 1.8 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 0.4 0.4
Total rabbi trust 0.1 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 15.1 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 37.7 46.6
Total Assets 37.7 46.6
Derivative Liability, Fair Value, Gross Liability 42.5 56.0
Total Liabilities 42.5 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 15.6 10.3
Total Assets 15.6 10.3
Derivative Liability, Fair Value, Gross Liability 5.2 7.2
Total Liabilities 5.2 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 63.7 62.8
Total rabbi trust 0.0 0.0
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total Assets 63.7 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 33.5 31.8
Evergy Kansas Central | Fair Value, Measurements, Recurring | NAV | Real estate securities fund    
Assets    
Total nuclear decommissioning trust 18.3 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 48.1 42.6
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (25.0) (59.7)
Derivative Liability 42.3 46.6
FIN 39 Derivative liability netting (16.7) (50.5)
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 21.0 45.5
Derivative Liability, Fair Value, Gross Liability 12.4 34.0
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 36.5 46.5
Derivative Liability, Fair Value, Gross Liability 41.4 55.9
Evergy Kansas Central | Fair Value, Measurements, Recurring | Power commodity contract | Level 3    
Assets    
Derivative Asset, Fair Value, Gross Asset 15.6 10.3
Derivative Liability, Fair Value, Gross Liability 5.2 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 10.9 7.3
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (102.2) (215.3)
Derivative Liability 3.3 1.4
FIN 39 Derivative liability netting (102.2) (215.3)
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 1    
Assets    
Derivative Asset, Fair Value, Gross Asset 111.9 222.5
Derivative Liability, Fair Value, Gross Liability 104.4 216.6
Evergy Kansas Central | Fair Value, Measurements, Recurring | Natural gas commodity contract | Level 2    
Assets    
Derivative Asset, Fair Value, Gross Asset 1.2 0.1
Derivative Liability, Fair Value, Gross Liability 1.1 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 120.0 112.5
Evergy Kansas Central | Domestic | Fair Value, Measurements, Recurring | Level 1 | Equity securities    
Assets    
Total nuclear decommissioning trust 108.1 100.4
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 11.9 12.1
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | Equity securities    
Assets    
Total nuclear decommissioning trust 67.3 62.9
Evergy Kansas Central | International | Fair Value, Measurements, Recurring | Level 1 | Equity securities    
Assets    
Total nuclear decommissioning trust 67.3 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 $ 354.4 $ 334.5
Derivative Asset 0.0 0.0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (2.2) (3.5)
Total self-insured health plan trust 12.0 11.2
Total Assets 366.4 345.7
Derivative Liability 3.6 0.6
FIN 39 Derivative liability netting (2.2) (3.5)
Total Liabilities 3.6 0.6
Evergy Metro | Fair Value, Measurements, Recurring | Equity securities    
Assets    
Total nuclear decommissioning trust 260.6 243.4
Total self-insured health plan trust 1.7 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Cash equivalents    
Assets    
Total nuclear decommissioning trust 4.5 6.6
Evergy Metro | Fair Value, Measurements, Recurring | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 44.5 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 4.3 4.2
Evergy Metro | Fair Value, Measurements, Recurring | Corporate bonds    
Assets    
Total nuclear decommissioning trust 40.4 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 6.6 8.0
Evergy Metro | Fair Value, Measurements, Recurring | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 3.7 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 1    
Assets    
Total nuclear decommissioning trust 309.6 291.1
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total self-insured health plan trust 7.2 5.7
Total Assets 316.8 296.8
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 260.6 243.4
Total self-insured health plan trust 1.7 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents    
Assets    
Total nuclear decommissioning trust 4.5 6.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury    
Assets    
Total nuclear decommissioning trust 44.5 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 1.8 2.5
Evergy Metro | Fair Value, Measurements, Recurring | Level 1 | Cash and cash equivalents    
Assets    
Total self-insured health plan trust 3.7 1.6
Evergy Metro | Fair Value, Measurements, Recurring | Level 2    
Assets    
Total nuclear decommissioning trust 44.8 43.4
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total self-insured health plan trust 4.8 5.5
Total Assets 49.6 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 4.3 4.2
Evergy Metro | Fair Value, Measurements, Recurring | Level 2 | Corporate bonds    
Assets    
Total nuclear decommissioning trust 40.4 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 4.8 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 2.2 3.5
Total self-insured health plan trust 0.0 0.0
Total Assets 2.2 3.5
Derivative Liability, Fair Value, Gross Liability 5.8 4.1
Total Liabilities 5.8 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 (2.2) (3.5)
Derivative Liability 3.6 0.6
FIN 39 Derivative liability netting (2.2) (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 2.2 3.5
Derivative Liability, Fair Value, Gross Liability 5.8 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 $ 9.3 $ 9.2
Derivative Asset 0.0 0.4
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (1.4) (1.0)
Total Assets 9.3 9.6
Derivative Liability 4.5 3.9
FIN 39 Derivative liability netting (1.4) (1.1)
Total Liabilities 4.5 3.9
Other Evergy | Fair Value, Measurements, Recurring | Core bond fund    
Assets    
Total rabbi trust 9.3 9.2
Other Evergy | Fair Value, Measurements, Recurring | Level 1    
Assets    
Total rabbi trust 9.3 9.2
Derivative Asset, Fair Value, Gross Asset 0.0 0.0
Total Assets 9.3 9.2
Derivative Liability, Fair Value, Gross Liability 1.3 0.2
Total Liabilities 1.3 0.2
Other Evergy | Fair Value, Measurements, Recurring | Level 1 | Core bond fund    
Assets    
Total rabbi trust 9.3 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 2.7 3.7
Total Liabilities 2.7 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 1.4 1.4
Total Assets 1.4 1.4
Derivative Liability, Fair Value, Gross Liability 1.9 1.1
Total Liabilities 1.9 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 0.0 0.4
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset (1.4) (1.0)
Derivative Liability 1.8 0.2
FIN 39 Derivative liability netting (1.4) (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 1.3 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 1.4 1.4
Derivative Liability, Fair Value, Gross Liability 1.9 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 2.7 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 2.7 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