Cash, Cash Equivalents and Short-Term Investments - Schedule of Amortized Cost, Unrealized Gains and Losses and Estimated Fair Value of Cash, Cash Equivalents and Short-Term Investments (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	$ 942.2	$ 1,328.3	$ 548.9
Cash and cash equivalents, estimated fair value	942.2	1,328.3
Short-term investments, amortized cost	242.7	272.9
Short-term investments, unrealized gain	0.2	0.2
Short-term investments, unrealized loss	(5.1)	(7.2)
Short-term investments, estimated fair value	237.8	265.9
Total cash, cash equivalents, and short term investments, before unrealized gains (losses) on investments	1,184.9	1,601.2
Total cash, cash equivalents, and short term investments	1,180.0	1,594.2
Corporate notes and obligations
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	114.9	133.1
Short-term investments, unrealized gain	0.2	0.2
Short-term investments, unrealized loss	(2.4)	(3.3)
Short-term investments, estimated fair value	112.7	130.0
U.S. Treasury securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	85.1	85.0
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	(1.8)	(2.6)
Short-term investments, estimated fair value	83.3	82.4
Municipal securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	24.5	30.0
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	(0.5)	(0.7)
Short-term investments, estimated fair value	24.0	29.3
Asset backed securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	12.6	19.2
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	(0.2)	(0.3)
Short-term investments, estimated fair value	12.4	18.9
U.S. agency obligations
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	3.8	3.8
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	(0.1)	(0.2)
Short-term investments, estimated fair value	3.7	3.6
Supranational securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	1.8	1.8
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	(0.1)	(0.1)
Short-term investments, estimated fair value	1.7	1.7
Cash
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	89.5	98.3
Cash and cash equivalents, estimated fair value	89.5	98.3
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	852.7	1,230.0
Cash and cash equivalents, estimated fair value	$ 852.7	$ 1,230.0

Cash, Cash Equivalents and Short-Term Investments - Schedule of Amortized Cost, Unrealized Gains and Losses and Estimated Fair Value of Cash, Cash Equivalents and Short-Term Investments (Details) - USD ($)
$ in Millions

Mar. 31, 2025

Dec. 31, 2024

Mar. 31, 2024

Cash and Cash Equivalents [Line Items]

Cash and cash equivalents, amortized cost

$ 942.2

$ 1,328.3

$ 548.9

Cash and cash equivalents, estimated fair value

942.2

1,328.3

Short-term investments, amortized cost