Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Mar. 31, 2023
Deferred tax assets:
Accrued expenses	$ 50.2	$ 64.7
Capital loss carryforward	10.5	11.0
Income tax credits	267.8	312.7
Intangible assets	1,374.8	1,328.7
Inventory valuation	72.0	40.0
Lease liabilities	36.2	35.8
Net operating loss carryforward	64.8	73.9
Property, plant and equipment	0.0	7.0
Share-based compensation	40.6	37.7
Other	15.5	4.0
Gross deferred tax assets	1,932.4	1,915.5
Valuation allowances	(270.8)	(299.4)
Deferred tax assets, net of valuation allowances	1,661.6	1,616.1
Deferred tax liabilities:
Intangible assets	(59.0)	(1.6)
ROU assets	(34.5)	(33.9)
Property, plant and equipment	(0.4)	0.0
Deferred tax liabilities	(93.9)	(35.5)
Net deferred tax asset	1,567.7	1,580.6
Reported as:
Non-current deferred tax assets	1,596.5	1,623.3
Non-current deferred tax liability	(28.8)	(42.7)
Net deferred tax asset	$ 1,567.7	$ 1,580.6