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FAIR VALUE MEASUREMENTS - NAV (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 USD ($) fund extension | Dec. 31, 2019 USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | $ 2.2 | $ 3.3
Evergy Kansas Central | Alternative investments fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 0.0 | 0.0
Evergy Kansas Central | Real estate securities fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 0.0 | 0.0
Evergy Kansas Central | Nuclear decommissioning trust: |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 2.2 | 3.3
Evergy Kansas Central | Core bond fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 0.0 | 0.0
Evergy Kansas Central | Combination debt/equity/other fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 0.0 | 0.0
Evergy Kansas Central | Rabbi trust: |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 0.0 | 0.0
Other Evergy |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | 0.0 | 0.0
Domestic | Evergy Kansas Central | Equity securities |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Unfunded Commitments | $ 2.2 | 3.3
NAV, number of funds | fund | 5 |
NAV, number of funds making distributions | fund | 3 |
Domestic | Evergy Kansas Central | Equity Securities - Fourth Fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Length of settlement | 15 years |
NAV, number of extensions | extension | 3 |
NAV, extension term | 1 year |
Domestic | Evergy Kansas Central | Equity Securities - Fifth Fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Length of settlement | 15 years |
Fair Value, Measurements, Recurring |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | $ 652.1 | 573.2
Total rabbi trust | 46.3 | 45.5
Total Assets | 711.6 | 628.6
Fair Value, Measurements, Recurring | Evergy Kansas Central |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 309.8 | 272.5
Total rabbi trust | 32.7 | 31.7
Total Assets | 342.5 | 304.2
Fair Value, Measurements, Recurring | Evergy Kansas Central | Alternative investments fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 23.2 | 23.9
Fair Value, Measurements, Recurring | Evergy Kansas Central | Real estate securities fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 12.9 | 12.6
Fair Value, Measurements, Recurring | Evergy Kansas Central | Core bond fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 40.6 | 39.3
Total rabbi trust | 25.6 | 25.3
Fair Value, Measurements, Recurring | Evergy Kansas Central | Combination debt/equity/other fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 20.1 | 16.4
Total rabbi trust | 7.1 | 6.3
Fair Value, Measurements, Recurring | Other Evergy |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total rabbi trust | 13.6 | 13.8
Fair Value, Measurements, Recurring | Domestic | Evergy Kansas Central | Equity securities |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 102.7 | 86.1
NAV | Fair Value, Measurements, Recurring |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 43.7 | 44.0
Total rabbi trust | 45.8 | 44.9
Total Assets | 89.5 | 88.9
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 43.7 | 44.0
Total rabbi trust | 32.7 | 31.6
Total Assets | 76.4 | 75.6
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central | Alternative investments fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | $ 23.2 | 23.9
Length of Settlement | 65 days |
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central | Real estate securities fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | $ 12.9 | 12.6
Length of Settlement | 65 days |
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central | Nuclear decommissioning trust: |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | $ 43.7 | 44.0
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central | Core bond fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 25.6 | 25.3
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central | Combination debt/equity/other fund |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 7.1 | 6.3
NAV | Fair Value, Measurements, Recurring | Evergy Kansas Central | Rabbi trust: |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total rabbi trust | 32.7 | 31.6
NAV | Fair Value, Measurements, Recurring | Other Evergy |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total rabbi trust | 13.1 | 13.3
NAV | Fair Value, Measurements, Recurring | Domestic | Evergy Kansas Central | Equity securities |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Total nuclear decommissioning trust | $ 7.6 | $ 7.5

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