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v3.25.1

Marketable Securities Held in Trusts - Continuous Loss Position (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2025 | Mar. 31, 2024 | Dec. 31, 2024
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | $ 133.9 |  | $ 136.9
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (7.2) |  | (8.4)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 338.7 |  | 436.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 2.4 |  | 10.2
Corporate debt securities |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 75.6 |  | 81.3
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (4.9) |  | (6.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 25.6 |  | 53.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0.2 |  | 0.7
Municipal bonds |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 58.3 |  | 55.6
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (2.3) |  | (2.3)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 91.8 |  | 102.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0.6 |  | 1.7
U.S. government bonds |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss |  |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 221.3 |  | 280.9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 1.6 |  | $ 7.8
Debt securities |  |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss |  |  |
Debt Securities, Available-for-sale, Realized Loss | $ 0.5 | $ 6.8 |

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