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	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	$ 1,056.2	$ 891.3	$ 736.3
Cash and cash equivalents, estimated fair value	1,056.2	891.3
Short-term investments, amortized cost	57.8	147.7
Short-term investments, unrealized gain	0.0	0.2
Short-term investments, unrealized loss	(0.2)	(1.0)
Short-term investments, estimated fair value	57.6	146.9
Total cash, cash equivalents, and short term investments, before unrealized gains (losses) on investments	1,114.0	1,039.0
Total cash, cash equivalents, and short term investments	1,113.8	1,038.2
Corporate notes and obligations
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	34.8	79.6
Short-term investments, unrealized gain	0.0	0.1
Short-term investments, unrealized loss	(0.2)	(0.6)
Short-term investments, estimated fair value	34.6	79.1
U.S. Treasury securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	11.7	45.4
Short-term investments, unrealized gain	0.0	0.1
Short-term investments, unrealized loss	0.0	(0.2)
Short-term investments, estimated fair value	11.7	45.3
Municipal securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	10.8	10.8
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	0.0	(0.1)
Short-term investments, estimated fair value	10.8	10.7
Asset backed securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost	0.5	6.3
Short-term investments, unrealized gain	0.0	0.0
Short-term investments, unrealized loss	0.0	(0.1)
Short-term investments, estimated fair value	0.5	6.2
U.S. agency obligations
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost		3.8
Short-term investments, unrealized gain		0.0
Short-term investments, unrealized loss		0.0
Short-term investments, estimated fair value		3.8
Supranational Securities
Cash and Cash Equivalents [Line Items]
Short-term investments, amortized cost		1.8
Short-term investments, unrealized gain		0.0
Short-term investments, unrealized loss		0.0
Short-term investments, estimated fair value		1.8
Cash
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	135.6	126.5
Cash and cash equivalents, estimated fair value	135.6	126.5
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	920.6	764.8
Cash and cash equivalents, estimated fair value	$ 920.6	$ 764.8

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

Jun. 30, 2026

Dec. 31, 2025

Jun. 30, 2025

Cash and Cash Equivalents [Line Items]

Cash and cash equivalents, amortized cost

$ 1,056.2

$ 891.3

$ 736.3

Cash and cash equivalents, estimated fair value

1,056.2

891.3

Short-term investments, amortized cost