Available-for-Sale Debt Securities - Fair Value of Available-For-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized cost, current	$ 765.4	$ 842.3
Unrealized gain, current	2.0	0.9
Unrealized loss, current	0.0	(0.1)
Fair value, current	767.4	843.1
Amortized cost, noncurrent	1,058.8	738.8
Unrealized gain, noncurrent	4.8	2.3
Unrealized loss, noncurrent	(0.6)	(1.6)
Fair value, noncurrent	1,063.0	739.5
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized cost, current	22.6	37.1
Unrealized gain, current	0.0	0.0
Unrealized loss, current	0.0	0.0
Fair value, current	22.6	37.1
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost, current	622.6	527.0
Unrealized gain, current	1.7	0.6
Unrealized loss, current	0.0	(0.1)
Fair value, current	624.3	527.5
Amortized cost, noncurrent	945.0	584.4
Unrealized gain, noncurrent	4.5	2.0
Unrealized loss, noncurrent	(0.5)	(1.0)
Fair value, noncurrent	949.0	585.4
Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Amortized cost, current	120.2	278.2
Unrealized gain, current	0.3	0.3
Unrealized loss, current	0.0	0.0
Fair value, current	120.5	278.5
Amortized cost, noncurrent	113.8	154.4
Unrealized gain, noncurrent	0.3	0.3
Unrealized loss, noncurrent	(0.1)	(0.6)
Fair value, noncurrent	$ 114.0	$ 154.1

Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Current

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