FAIR VALUE MEASUREMENTS - Recurring (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions | Jun. 30, 2021 | Dec. 31, 2020 |
Assets | | |
Total nuclear decommissioning trust | $ 729.4 | $ 652.1 |
Total rabbi trust | 44.8 | 46.3 |
Total self-insured health plan trust | 13.7 | 13.2 |
Total Assets | 787.9 | 711.6 |
Level 1 | | |
Assets | | |
Total nuclear decommissioning trust | 627 | 560.6 |
Total rabbi trust | 44.8 | 0.5 |
Total self-insured health plan trust | 7.6 | 8 |
Total Assets | 679.4 | 569.1 |
Level 2 | | |
Assets | | |
Total nuclear decommissioning trust | 48.6 | 47.8 |
Total rabbi trust | 0 | 0 |
Total self-insured health plan trust | 6.1 | 5.2 |
Total Assets | 54.7 | 53 |
Level 3 | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | 0 |
Total self-insured health plan trust | 0 | 0 |
Total Assets | 0 | 0 |
NAV | | |
Assets | | |
Total nuclear decommissioning trust | 53.8 | 43.7 |
Total rabbi trust | 0 | 45.8 |
Total self-insured health plan trust | 0 | 0 |
Total Assets | 53.8 | 89.5 |
Evergy Kansas Central | | |
Assets | | |
Total nuclear decommissioning trust | 349.6 | 309.8 |
Total rabbi trust | 32.1 | 32.7 |
Total Assets | 381.7 | 342.5 |
Evergy Kansas Central | Core bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 50.6 | 40.6 |
Total rabbi trust | | 25.6 |
Evergy Kansas Central | High-yield bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 29 | 25 |
Evergy Kansas Central | Emerging markets bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 25.2 | 21 |
Evergy Kansas Central | Equity funds | | |
Assets | | |
Total rabbi trust | 4.9 | |
Evergy Kansas Central | Combination debt/equity/other fund | | |
Assets | | |
Total nuclear decommissioning trust | 21.7 | 20.1 |
Total rabbi trust | 0.7 | 7.1 |
Evergy Kansas Central | Alternative investments fund | | |
Assets | | |
Total nuclear decommissioning trust | 30.2 | 23.2 |
Evergy Kansas Central | Real estate securities fund | | |
Assets | | |
Total nuclear decommissioning trust | 13.5 | 12.9 |
Evergy Kansas Central | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0.5 | 0.5 |
Total rabbi trust | 0.1 | |
Evergy Kansas Central | Other | | |
Assets | | |
Total nuclear decommissioning trust | (0.4) | |
Evergy Kansas Central | Fixed income funds | | |
Assets | | |
Total rabbi trust | 26.4 | |
Evergy Kansas Central | Level 1 | | |
Assets | | |
Total nuclear decommissioning trust | 296.2 | 266.1 |
Total rabbi trust | 32.1 | 0 |
Total Assets | 328.3 | 266.1 |
Evergy Kansas Central | Level 1 | Core bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 50.6 | 40.6 |
Total rabbi trust | | 0 |
Evergy Kansas Central | Level 1 | High-yield bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 29 | 25 |
Evergy Kansas Central | Level 1 | Emerging markets bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 25.2 | 21 |
Evergy Kansas Central | Level 1 | Equity funds | | |
Assets | | |
Total rabbi trust | 4.9 | |
Evergy Kansas Central | Level 1 | Combination debt/equity/other fund | | |
Assets | | |
Total nuclear decommissioning trust | 21.7 | 20.1 |
Total rabbi trust | 0.7 | 0 |
Evergy Kansas Central | Level 1 | Alternative investments fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 1 | Real estate securities fund | | |
Assets | | |
Total nuclear decommissioning trust | 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 1 | Other | | |
Assets | | |
Total nuclear decommissioning trust | 0 | |
Evergy Kansas Central | Level 1 | Fixed income funds | | |
Assets | | |
Total rabbi trust | 26.4 | |
Evergy Kansas Central | Level 2 | | |
Assets | | |
Total nuclear decommissioning trust | (0.4) | 0 |
Total rabbi trust | 0 | 0 |
Total Assets | (0.4) | 0 |
Evergy Kansas Central | Level 2 | Core bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | | 0 |
Evergy Kansas Central | Level 2 | High-yield bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 2 | Emerging markets bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 2 | Equity funds | | |
Assets | | |
Total rabbi trust | 0 | |
Evergy Kansas Central | Level 2 | Combination debt/equity/other fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | 0 |
Evergy Kansas Central | Level 2 | Alternative investments fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 2 | Real estate securities fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 2 | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | |
Evergy Kansas Central | Level 2 | Other | | |
Assets | | |
Total nuclear decommissioning trust | (0.4) | |
Evergy Kansas Central | Level 2 | Fixed income funds | | |
Assets | | |
Total rabbi trust | 0 | |
Evergy Kansas Central | Level 3 | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | 0 |
Total Assets | 0 | 0 |
Evergy Kansas Central | Level 3 | Core bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | | 0 |
Evergy Kansas Central | Level 3 | High-yield bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 3 | Emerging markets bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 3 | Equity funds | | |
Assets | | |
Total rabbi trust | 0 | |
Evergy Kansas Central | Level 3 | Combination debt/equity/other fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | 0 |
Evergy Kansas Central | Level 3 | Alternative investments fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 3 | Real estate securities fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Level 3 | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | |
Evergy Kansas Central | Level 3 | Other | | |
Assets | | |
Total nuclear decommissioning trust | 0 | |
Evergy Kansas Central | Level 3 | Fixed income funds | | |
Assets | | |
Total rabbi trust | 0 | |
Evergy Kansas Central | NAV | | |
Assets | | |
Total nuclear decommissioning trust | 53.8 | 43.7 |
Total rabbi trust | 0 | 32.7 |
Total Assets | 53.8 | 76.4 |
Evergy Kansas Central | NAV | Core bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | 25.6 |
Evergy Kansas Central | NAV | High-yield bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | NAV | Emerging markets bond fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | NAV | Equity funds | | |
Assets | | |
Total rabbi trust | 0 | |
Evergy Kansas Central | NAV | Combination debt/equity/other fund | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | 7.1 |
Evergy Kansas Central | NAV | Alternative investments fund | | |
Assets | | |
Total nuclear decommissioning trust | 30.2 | 23.2 |
Evergy Kansas Central | NAV | Real estate securities fund | | |
Assets | | |
Total nuclear decommissioning trust | 13.5 | 12.9 |
Evergy Kansas Central | NAV | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total rabbi trust | 0 | |
Evergy Kansas Central | NAV | Other | | |
Assets | | |
Total nuclear decommissioning trust | 0 | |
Evergy Kansas Central | NAV | Fixed income funds | | |
Assets | | |
Total rabbi trust | 0 | |
Evergy Kansas Central | Domestic | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 111.2 | 102.7 |
Evergy Kansas Central | Domestic | Level 1 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 101.1 | 95.1 |
Evergy Kansas Central | Domestic | Level 2 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Domestic | Level 3 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | Domestic | NAV | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 10.1 | 7.6 |
Evergy Kansas Central | International | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 68.1 | 63.8 |
Evergy Kansas Central | International | Level 1 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 68.1 | 63.8 |
Evergy Kansas Central | International | Level 2 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | International | Level 3 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Kansas Central | International | NAV | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | | |
Assets | | |
Total nuclear decommissioning trust | 379.8 | 342.3 |
Total self-insured health plan trust | 13.7 | 13.2 |
Total Assets | 393.5 | 355.5 |
Evergy Metro | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 280.9 | 243.1 |
Total self-insured health plan trust | 1.9 | 1.7 |
Evergy Metro | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 4.8 | 3.2 |
Evergy Metro | U.S. Treasury | | |
Assets | | |
Total nuclear decommissioning trust | 45.1 | 47.7 |
Evergy Metro | U.S. Agency | | |
Assets | | |
Total nuclear decommissioning trust | 0.4 | 0.5 |
Evergy Metro | State and local obligations | | |
Assets | | |
Total nuclear decommissioning trust | 4.1 | 4.1 |
Evergy Metro | Corporate bonds | | |
Assets | | |
Total nuclear decommissioning trust | 44.4 | 43.1 |
Evergy Metro | Foreign governments | | |
Assets | | |
Total nuclear decommissioning trust | 0.1 | 0.1 |
Evergy Metro | Other | | |
Assets | | |
Total nuclear decommissioning trust | | 0.5 |
Evergy Metro | Debt securities | | |
Assets | | |
Total self-insured health plan trust | 9.1 | 8 |
Evergy Metro | Cash and cash equivalents | | |
Assets | | |
Total self-insured health plan trust | 2.7 | 3.5 |
Evergy Metro | Level 1 | | |
Assets | | |
Total nuclear decommissioning trust | 330.8 | 294.5 |
Total self-insured health plan trust | 7.6 | 8 |
Total Assets | 338.4 | 302.5 |
Evergy Metro | Level 1 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 280.9 | 243.1 |
Total self-insured health plan trust | 1.9 | 1.7 |
Evergy Metro | Level 1 | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 4.8 | 3.2 |
Evergy Metro | Level 1 | U.S. Treasury | | |
Assets | | |
Total nuclear decommissioning trust | 45.1 | 47.7 |
Evergy Metro | Level 1 | U.S. Agency | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 1 | State and local obligations | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 1 | Corporate bonds | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 1 | Foreign governments | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 1 | Other | | |
Assets | | |
Total nuclear decommissioning trust | | 0.5 |
Evergy Metro | Level 1 | Debt securities | | |
Assets | | |
Total self-insured health plan trust | 3 | 2.8 |
Evergy Metro | Level 1 | Cash and cash equivalents | | |
Assets | | |
Total self-insured health plan trust | 2.7 | 3.5 |
Evergy Metro | Level 2 | | |
Assets | | |
Total nuclear decommissioning trust | 49 | 47.8 |
Total self-insured health plan trust | 6.1 | 5.2 |
Total Assets | 55.1 | 53 |
Evergy Metro | Level 2 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | Level 2 | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 2 | U.S. Treasury | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 2 | U.S. Agency | | |
Assets | | |
Total nuclear decommissioning trust | 0.4 | 0.5 |
Evergy Metro | Level 2 | State and local obligations | | |
Assets | | |
Total nuclear decommissioning trust | 4.1 | 4.1 |
Evergy Metro | Level 2 | Corporate bonds | | |
Assets | | |
Total nuclear decommissioning trust | 44.4 | 43.1 |
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 |
Evergy Metro | Level 2 | Debt securities | | |
Assets | | |
Total self-insured health plan trust | 6.1 | 5.2 |
Evergy Metro | Level 2 | Cash and cash equivalents | | |
Assets | | |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | Level 3 | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total self-insured health plan trust | 0 | 0 |
Total Assets | 0 | 0 |
Evergy Metro | Level 3 | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | Level 3 | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 3 | U.S. Treasury | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 3 | U.S. Agency | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 3 | State and local obligations | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 3 | Corporate bonds | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 3 | Foreign governments | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | Level 3 | Other | | |
Assets | | |
Total nuclear decommissioning trust | | 0 |
Evergy Metro | Level 3 | Debt securities | | |
Assets | | |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | Level 3 | Cash and cash equivalents | | |
Assets | | |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | NAV | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total self-insured health plan trust | 0 | 0 |
Total Assets | 0 | 0 |
Evergy Metro | NAV | Equity securities | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | NAV | Cash equivalents | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | NAV | U.S. Treasury | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | NAV | U.S. Agency | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | NAV | State and local obligations | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | NAV | Corporate bonds | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | NAV | Foreign governments | | |
Assets | | |
Total nuclear decommissioning trust | 0 | 0 |
Evergy Metro | NAV | Other | | |
Assets | | |
Total nuclear decommissioning trust | | 0 |
Evergy Metro | NAV | Debt securities | | |
Assets | | |
Total self-insured health plan trust | 0 | 0 |
Evergy Metro | NAV | Cash and cash equivalents | | |
Assets | | |
Total self-insured health plan trust | 0 | 0 |
Other Evergy | | |
Assets | | |
Total rabbi trust | 12.7 | 13.6 |
Other Evergy | Core bond fund | | |
Assets | | |
Total rabbi trust | 12.7 | |
Other Evergy | Fixed income funds | | |
Assets | | |
Total rabbi trust | | 13.1 |
Other Evergy | Cash and cash equivalents | | |
Assets | | |
Total rabbi trust | | 0.5 |
Other Evergy | Level 1 | | |
Assets | | |
Total rabbi trust | 12.7 | 0.5 |
Other Evergy | Level 1 | Core bond fund | | |
Assets | | |
Total rabbi trust | 12.7 | |
Other Evergy | Level 1 | Fixed income funds | | |
Assets | | |
Total rabbi trust | | 0 |
Other Evergy | Level 1 | Cash and cash equivalents | | |
Assets | | |
Total rabbi trust | | 0.5 |
Other Evergy | Level 2 | | |
Assets | | |
Total rabbi trust | 0 | 0 |
Other Evergy | Level 2 | Core bond fund | | |
Assets | | |
Total rabbi trust | 0 | |
Other Evergy | Level 2 | Fixed income funds | | |
Assets | | |
Total rabbi trust | | 0 |
Other Evergy | Level 2 | Cash and cash equivalents | | |
Assets | | |
Total rabbi trust | | 0 |
Other Evergy | Level 3 | | |
Assets | | |
Total rabbi trust | 0 | 0 |
Other Evergy | Level 3 | Core bond fund | | |
Assets | | |
Total rabbi trust | 0 | |
Other Evergy | Level 3 | Fixed income funds | | |
Assets | | |
Total rabbi trust | | 0 |
Other Evergy | Level 3 | Cash and cash equivalents | | |
Assets | | |
Total rabbi trust | | 0 |
Other Evergy | NAV | | |
Assets | | |
Total rabbi trust | 0 | 13.1 |
Other Evergy | NAV | Core bond fund | | |
Assets | | |
Total rabbi trust | $ 0 | |
Other Evergy | NAV | Fixed income funds | | |
Assets | | |
Total rabbi trust | | 13.1 |
Other Evergy | NAV | Cash and cash equivalents | | |
Assets | | |
Total rabbi trust | | $ 0 |