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FAIR VALUE MEASUREMENTS - Recurring (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Assets |  |
Total nuclear decommissioning trust | $ 652.1 | $ 573.2
Total rabbi trust | 46.3 | 45.5
Total self-insured health plan trust | 13.2 | 9.9
Total Assets | 711.6 | 628.6
Level 1 |  |
Assets |  |
Total nuclear decommissioning trust | 560.6 | 493.0
Total rabbi trust | 0.5 | 0.6
Total self-insured health plan trust | 8.0 | 4.6
Total Assets | 569.1 | 498.2
Level 2 |  |
Assets |  |
Total nuclear decommissioning trust | 47.8 | 36.2
Total rabbi trust | 0.0 | 0.0
Total self-insured health plan trust | 5.2 | 5.3
Total Assets | 53.0 | 41.5
Level 3 |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Total self-insured health plan trust | 0.0 | 0.0
Total Assets | 0.0 | 0.0
NAV |  |
Assets |  |
Total nuclear decommissioning trust | 43.7 | 44.0
Total rabbi trust | 45.8 | 44.9
Total self-insured health plan trust | 0.0 | 0.0
Total Assets | 89.5 | 88.9
Evergy Kansas Central |  |
Assets |  |
Total nuclear decommissioning trust | 309.8 | 272.5
Total rabbi trust | 32.7 | 31.7
Total Assets | 342.5 | 304.2
Evergy Kansas Central | Core bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 40.6 | 39.3
Total rabbi trust | 25.6 | 25.3
Evergy Kansas Central | High-yield bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 25.0 | 22.3
Evergy Kansas Central | Emerging markets bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 21.0 | 19.4
Evergy Kansas Central | Combination debt/equity/other fund |  |
Assets |  |
Total nuclear decommissioning trust | 20.1 | 16.4
Total rabbi trust | 7.1 | 6.3
Evergy Kansas Central | Alternative investments fund |  |
Assets |  |
Total nuclear decommissioning trust | 23.2 | 23.9
Evergy Kansas Central | Real estate securities fund |  |
Assets |  |
Total nuclear decommissioning trust | 12.9 | 12.6
Evergy Kansas Central | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.5 | 0.5
Total rabbi trust |  | 0.1
Evergy Kansas Central | Level 1 |  |
Assets |  |
Total nuclear decommissioning trust | 266.1 | 228.5
Total rabbi trust | 0.0 | 0.1
Total Assets | 266.1 | 228.6
Evergy Kansas Central | Level 1 | Core bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 40.6 | 39.3
Total rabbi trust | 0.0 | 0.0
Evergy Kansas Central | Level 1 | High-yield bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 25.0 | 22.3
Evergy Kansas Central | Level 1 | Emerging markets bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 21.0 | 19.4
Evergy Kansas Central | Level 1 | Combination debt/equity/other fund |  |
Assets |  |
Total nuclear decommissioning trust | 20.1 | 16.4
Total rabbi trust | 0.0 | 0.0
Evergy Kansas Central | Level 1 | Alternative investments fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 1 | Real estate securities fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 1 | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.5 | 0.5
Total rabbi trust |  | 0.1
Evergy Kansas Central | Level 2 |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Total Assets | 0.0 | 0.0
Evergy Kansas Central | Level 2 | Core bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Evergy Kansas Central | Level 2 | High-yield bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 2 | Emerging markets bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 2 | Combination debt/equity/other fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Evergy Kansas Central | Level 2 | Alternative investments fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 2 | Real estate securities fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 2 | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust |  | 0.0
Evergy Kansas Central | Level 3 |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Total Assets | 0.0 | 0.0
Evergy Kansas Central | Level 3 | Core bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Evergy Kansas Central | Level 3 | High-yield bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 3 | Emerging markets bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 3 | Combination debt/equity/other fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 0.0 | 0.0
Evergy Kansas Central | Level 3 | Alternative investments fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 3 | Real estate securities fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Level 3 | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust |  | 0.0
Evergy Kansas Central | NAV |  |
Assets |  |
Total nuclear decommissioning trust | 43.7 | 44.0
Total rabbi trust | 32.7 | 31.6
Total Assets | 76.4 | 75.6
Evergy Kansas Central | NAV | Core bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 25.6 | 25.3
Evergy Kansas Central | NAV | High-yield bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | NAV | Emerging markets bond fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | NAV | Combination debt/equity/other fund |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust | 7.1 | 6.3
Evergy Kansas Central | NAV | Alternative investments fund |  |
Assets |  |
Total nuclear decommissioning trust | 23.2 | 23.9
Evergy Kansas Central | NAV | Real estate securities fund |  |
Assets |  |
Total nuclear decommissioning trust | 12.9 | 12.6
Evergy Kansas Central | NAV | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total rabbi trust |  | 0.0
Evergy Kansas Central | Domestic | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 102.7 | 86.1
Evergy Kansas Central | Domestic | Level 1 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 95.1 | 78.6
Evergy Kansas Central | Domestic | Level 2 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Domestic | Level 3 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | Domestic | NAV | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 7.6 | 7.5
Evergy Kansas Central | International | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 63.8 | 52.0
Evergy Kansas Central | International | Level 1 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 63.8 | 52.0
Evergy Kansas Central | International | Level 2 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | International | Level 3 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Kansas Central | International | NAV | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro |  |
Assets |  |
Total nuclear decommissioning trust | 342.3 | 300.7
Total self-insured health plan trust | 13.2 | 9.9
Total Assets | 355.5 | 310.6
Evergy Metro | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 243.1 | 211.1
Total self-insured health plan trust | 1.7 | 0.5
Evergy Metro | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 3.2 | 3.1
Evergy Metro | U.S. Treasury |  |
Assets |  |
Total nuclear decommissioning trust | 47.7 | 50.3
Evergy Metro | U.S. Agency |  |
Assets |  |
Total nuclear decommissioning trust | 0.5 | 0.4
Evergy Metro | State and local obligations |  |
Assets |  |
Total nuclear decommissioning trust | 4.1 | 2.2
Evergy Metro | Corporate bonds |  |
Assets |  |
Total nuclear decommissioning trust | 43.1 | 33.2
Evergy Metro | Foreign governments |  |
Assets |  |
Total nuclear decommissioning trust | 0.1 | 0.1
Evergy Metro | Other |  |
Assets |  |
Total nuclear decommissioning trust | 0.5 | 0.3
Evergy Metro | Debt securities |  |
Assets |  |
Total self-insured health plan trust | 8.0 | 6.7
Evergy Metro | Cash and cash equivalents |  |
Assets |  |
Total self-insured health plan trust | 3.5 | 2.7
Evergy Metro | Level 1 |  |
Assets |  |
Total nuclear decommissioning trust | 294.5 | 264.5
Total self-insured health plan trust | 8.0 | 4.6
Total Assets | 302.5 | 269.1
Evergy Metro | Level 1 | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 243.1 | 211.1
Total self-insured health plan trust | 1.7 | 0.5
Evergy Metro | Level 1 | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 3.2 | 3.1
Evergy Metro | Level 1 | U.S. Treasury |  |
Assets |  |
Total nuclear decommissioning trust | 47.7 | 50.3
Evergy Metro | Level 1 | U.S. Agency |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 1 | State and local obligations |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 1 | Corporate bonds |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 1 | Foreign governments |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 1 | Other |  |
Assets |  |
Total nuclear decommissioning trust | 0.5 | 0.0
Evergy Metro | Level 1 | Debt securities |  |
Assets |  |
Total self-insured health plan trust | 2.8 | 1.4
Evergy Metro | Level 1 | Cash and cash equivalents |  |
Assets |  |
Total self-insured health plan trust | 3.5 | 2.7
Evergy Metro | Level 2 |  |
Assets |  |
Total nuclear decommissioning trust | 47.8 | 36.2
Total self-insured health plan trust | 5.2 | 5.3
Total Assets | 53.0 | 41.5
Evergy Metro | 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 | Level 2 | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 2 | U.S. Treasury |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 2 | U.S. Agency |  |
Assets |  |
Total nuclear decommissioning trust | 0.5 | 0.4
Evergy Metro | Level 2 | State and local obligations |  |
Assets |  |
Total nuclear decommissioning trust | 4.1 | 2.2
Evergy Metro | Level 2 | Corporate bonds |  |
Assets |  |
Total nuclear decommissioning trust | 43.1 | 33.2
Evergy Metro | Level 2 | Foreign governments |  |
Assets |  |
Total nuclear decommissioning trust | 0.1 | 0.1
Evergy Metro | Level 2 | Other |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.3
Evergy Metro | Level 2 | Debt securities |  |
Assets |  |
Total self-insured health plan trust | 5.2 | 5.3
Evergy Metro | Level 2 | Cash and cash equivalents |  |
Assets |  |
Total self-insured health plan trust | 0.0 | 0.0
Evergy Metro | Level 3 |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total self-insured health plan trust | 0.0 | 0.0
Total Assets | 0.0 | 0.0
Evergy Metro | 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 | Level 3 | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | U.S. Treasury |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | U.S. Agency |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | State and local obligations |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | Corporate bonds |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | Foreign governments |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | Other |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | Level 3 | Debt securities |  |
Assets |  |
Total self-insured health plan trust | 0.0 | 0.0
Evergy Metro | Level 3 | Cash and cash equivalents |  |
Assets |  |
Total self-insured health plan trust | 0.0 | 0.0
Evergy Metro | NAV |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total self-insured health plan trust | 0.0 | 0.0
Total Assets | 0.0 | 0.0
Evergy Metro | NAV | Equity securities |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Total self-insured health plan trust | 0.0 | 0.0
Evergy Metro | NAV | Cash equivalents |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | U.S. Treasury |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | U.S. Agency |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | State and local obligations |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | Corporate bonds |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | Foreign governments |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | Other |  |
Assets |  |
Total nuclear decommissioning trust | 0.0 | 0.0
Evergy Metro | NAV | Debt securities |  |
Assets |  |
Total self-insured health plan trust | 0.0 | 0.0
Evergy Metro | NAV | Cash and cash equivalents |  |
Assets |  |
Total self-insured health plan trust | 0.0 | 0.0
Other Evergy |  |
Assets |  |
Total rabbi trust | 13.6 | 13.8
Other Evergy | Fixed income fund |  |
Assets |  |
Total rabbi trust | 13.1 | 13.3
Other Evergy | Cash and cash equivalents |  |
Assets |  |
Total rabbi trust | 0.5 | 0.5
Other Evergy | Level 1 |  |
Assets |  |
Total rabbi trust | 0.5 | 0.5
Other Evergy | Level 1 | Fixed income fund |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | Level 1 | Cash and cash equivalents |  |
Assets |  |
Total rabbi trust | 0.5 | 0.5
Other Evergy | Level 2 |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | Level 2 | Fixed income fund |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | Level 2 | Cash and cash equivalents |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | Level 3 |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | Level 3 | Fixed income fund |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | Level 3 | Cash and cash equivalents |  |
Assets |  |
Total rabbi trust | 0.0 | 0.0
Other Evergy | NAV |  |
Assets |  |
Total rabbi trust | 13.1 | 13.3
Other Evergy | NAV | Fixed income fund |  |
Assets |  |
Total rabbi trust | 13.1 | 13.3
Other Evergy | NAV | Cash and cash equivalents |  |
Assets |  |
Total rabbi trust | $ 0.0 | $ 0.0

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- Definition The fair value of investments held in a trust for KCP&L's self-insurance health plan. + References No definition available. + Details
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- Definition The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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