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Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - Fair Value Measured on a Recurring Basis - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Financial Assets
Investments in equity securities	$ 48.0	$ 37.9
Investments in debt securities	119.3	423.1
Financial Liabilities
Contingent payment obligations	7.9	14.7
Affiliate equity purchase obligations	53.9	53.9
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets
Investments in equity securities	48.0	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
Significant Other Observable Inputs (Level 2)
Financial Assets
Investments in equity securities	0.0	0.0
Investments in debt securities	119.3	423.1
Financial Liabilities
Contingent payment obligations	0.0	0.0
Affiliate equity purchase obligations	0.0	0.0
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	7.9	14.7
Affiliate equity purchase obligations	$ 53.9	$ 53.9

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