FAIR VALUE MEASUREMENTS - Schedule of Valuation of Financial Instruments Carried at Fair Value by the Applicable Pricing Categories (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Liabilities:
Carrying value of goodwill	$ 3,320.2	$ 3,529.1	$ 3,490.4
Rare Diseases Reporting Unit
Liabilities:
Carrying value of goodwill		118.9	$ 208.9
Recurring | Level 1
Assets:
Investment securities	0.0	0.1
Total assets	0.0	0.1
Liabilities:
Total liabilities	0.0	0.0
Recurring | Level 1 | Foreign currency forward contracts
Assets:
Derivative assets	0.0	0.0
Liabilities:
Derivative liabilities	0.0	0.0
Recurring | Level 1 | Cross-currency swaps
Assets:
Derivative assets	0.0	0.0
Liabilities:
Derivative liabilities	0.0	0.0
Recurring | Level 1 | Interest rate swap agreements
Assets:
Derivative assets	0.0	0.0
Liabilities:
Derivative liabilities	0.0	0.0
Recurring | Level 2
Assets:
Investment securities	0.0	0.0
Total assets	29.0	31.1
Liabilities:
Total liabilities	75.0	186.4
Recurring | Level 2 | Foreign currency forward contracts
Assets:
Derivative assets	5.5	0.6
Liabilities:
Derivative liabilities	5.6	2.7
Recurring | Level 2 | Cross-currency swaps
Assets:
Derivative assets	14.2	0.0
Liabilities:
Derivative liabilities	46.8	172.0
Recurring | Level 2 | Interest rate swap agreements
Assets:
Derivative assets	9.3	30.5
Liabilities:
Derivative liabilities	22.6	11.7
Recurring | Level 3
Assets:
Investment securities	0.0	0.0
Total assets	0.0	0.0
Liabilities:
Total liabilities	0.0	0.0
Recurring | Level 3 | Foreign currency forward contracts
Assets:
Derivative assets	0.0	0.0
Liabilities:
Derivative liabilities	0.0	0.0
Recurring | Level 3 | Cross-currency swaps
Assets:
Derivative assets	0.0	0.0
Liabilities:
Derivative liabilities	0.0	0.0
Recurring | Level 3 | Interest rate swap agreements
Assets:
Derivative assets	0.0	0.0
Liabilities:
Derivative liabilities	0.0	0.0
Nonrecurring | Level 1
Assets:
Goodwill	0.0	0.0
Contingent consideration	0.0	0.0
Total assets	0.0	0.0
Nonrecurring | Level 2
Assets:
Goodwill	0.0	0.0
Contingent consideration	0.0	0.0
Total assets	0.0	0.0
Nonrecurring | Level 3
Assets:
Goodwill	0.0	118.9
Contingent consideration	34.5	0.0
Total assets	$ 34.5	$ 118.9