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Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Financial Liabilities |  |
Contingent payment obligations | $ 9.6 |
Fair Value Measured on a Recurring Basis |  |
Financial Assets |  |
Investments in equity securities | 34.1 | $ 37.9
Investments in debt securities | 314.8 | 423.1
Financial Liabilities |  |
Contingent payment obligations | 9.6 | 14.7
Affiliate equity purchase obligations | 37.7 | 53.9
Fair Value Measured on a Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |
Financial Assets |  |
Investments in equity securities | 34.1 | 37.9
Investments in debt securities | 0.0 | 0.0
Financial Liabilities |  |
Contingent payment obligations | 0.0 | 0.0
Affiliate equity purchase obligations | 0.0 | 0.0
Fair Value Measured on a Recurring Basis | Significant Other Observable Inputs (Level 2) |  |
Financial Assets |  |
Investments in equity securities | 0.0 | 0.0
Investments in debt securities | 314.8 | 423.1
Financial Liabilities |  |
Contingent payment obligations | 0.0 | 0.0
Affiliate equity purchase obligations | 0.0 | 0.0
Fair Value Measured on a Recurring Basis | Significant Unobservable Inputs (Level 3) |  |
Financial Assets |  |
Investments in equity securities | 0.0 | 0.0
Investments in debt securities | 0.0 | 0.0
Financial Liabilities |  |
Contingent payment obligations | 9.6 | 14.7
Affiliate equity purchase obligations | $ 37.7 | $ 53.9

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