Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net unrealized gains (losses)	$ (237.8)	$ (39.8)	$ 386.1
Write-down in other income (expense)	29.0
Securities owned not readily marketable	74.3	48.3
Fair value adjustments of contingent consideration	0.0
Level 2 | Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 1,528.0	$ 1,443.0