Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Net operating loss carry-forwards	$ 32.2	$ 44.4
Research and other credit carry-forwards	295.8	294.4
Deferred revenue	131.5	74.9
Share-based compensation	20.7	25.4
Capitalized R&D expenditure	624.7	475.7
Reserves and accruals not currently deductible	140.0	133.0
Operating lease liabilities	43.2	31.9
Other	13.0	12.1
Total deferred tax assets	1,301.1	1,091.8
Valuation allowance	(331.2)	(326.9)
Deferred tax assets, net of valuation allowance	969.9	764.9
Deferred tax liabilities:
Property and equipment basis differences	(0.1)	(5.5)
Purchased intangible assets	(14.4)	(23.0)
Unremitted foreign earnings	(24.1)	(24.1)
Net unrealized gain	(30.9)	(41.9)
Operating lease assets	(38.0)	(29.5)
Total deferred tax liabilities	(107.5)	(124.0)
Net deferred tax assets	$ 862.4	$ 640.9