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PENSION AND POST-RETIREMENT PLANS - FAIR VALUE (Details) - Pension Benefits - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Pension and Post-retirement Plans |  |  |
Total | $ 212.8 | $ 194.8 | $ 162.2
Fair Value Measurement |  |  |
Pension and Post-retirement Plans |  |  |
Total | 170.9 | 157.3 |
Total plan assets | 212.8 | 194.8 |
Fair Value Measurement | Cash |  |  |
Pension and Post-retirement Plans |  |  |
Total | 3.8 | 6.3 |
Fair Value Measurement | U.S. large-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 71.3 | 62.4 |
Fair Value Measurement | U.S. mid- and small-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 54.3 | 49.6 |
Fair Value Measurement | International large-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 7.0 | 6.6 |
Fair Value Measurement | U.S. Treasuries |  |  |
Pension and Post-retirement Plans |  |  |
Total | 12.0 | 14.1 |
Fair Value Measurement | Investment grade U.S. corporate bonds |  |  |
Pension and Post-retirement Plans |  |  |
Total | 22.5 | 18.2 |
Fair Value Measurement | High-yield U.S. corporate bonds |  |  |
Pension and Post-retirement Plans |  |  |
Total |  | 0.1 |
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) |  |  |
Pension and Post-retirement Plans |  |  |
Total | 68.9 | 63.9 |
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | Cash |  |  |
Pension and Post-retirement Plans |  |  |
Total | 3.8 | 6.3 |
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | U.S. large-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 28.9 | 23.7 |
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | U.S. mid- and small-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 36.2 | 33.9 |
Fair Value Measurement | Significant Observable Inputs (Level 2) |  |  |
Pension and Post-retirement Plans |  |  |
Total | 102.0 | 93.4 |
Fair Value Measurement | Significant Observable Inputs (Level 2) | U.S. large-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 42.4 | 38.7 |
Fair Value Measurement | Significant Observable Inputs (Level 2) | U.S. mid- and small-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 18.1 | 15.7 |
Fair Value Measurement | Significant Observable Inputs (Level 2) | International large-cap |  |  |
Pension and Post-retirement Plans |  |  |
Total | 7.0 | 6.6 |
Fair Value Measurement | Significant Observable Inputs (Level 2) | U.S. Treasuries |  |  |
Pension and Post-retirement Plans |  |  |
Total | 12.0 | 14.1 |
Fair Value Measurement | Significant Observable Inputs (Level 2) | Investment grade U.S. corporate bonds |  |  |
Pension and Post-retirement Plans |  |  |
Total | 22.5 | 18.2 |
Fair Value Measurement | Significant Observable Inputs (Level 2) | High-yield U.S. corporate bonds |  |  |
Pension and Post-retirement Plans |  |  |
Total |  | 0.1 |
Fair Value Measurement | Investment measured at NAV |  |  |
Pension and Post-retirement Plans |  |  |
Total | $ 41.9 | $ 37.5 |

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