Fair Value Measurements - Changes in Level 3 Liabilities (Details) - Significant Unobservable Inputs (Level 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Contingent Payment Obligations
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 9.6	$ 22.9	$ 14.7	$ 21.0
Purchases and issuances	0.0	0.0	0.0	0.0
Settlements and reductions	0.0	0.0	0.0	0.0
Net realized and unrealized (gains) losses	(1.7)	0.5	(6.8)	2.4
Balance, end of period	7.9	23.4	7.9	23.4
Net change in unrealized (gains) losses relating to instruments still held at the reporting date	(1.7)	0.5	(6.8)	2.4
Affiliate Equity Purchase Obligations
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	37.7	60.9	53.9	24.5
Purchases and issuances	31.3	26.8	56.2	71.0
Settlements and reductions	(16.6)	(16.8)	(57.1)	(24.3)
Net realized and unrealized (gains) losses	1.5	(2.5)	0.9	(2.8)
Balance, end of period	53.9	68.4	53.9	68.4
Net change in unrealized (gains) losses relating to instruments still held at the reporting date	$ 1.5	$ (1.8)	$ 0.9	$ (2.1)