Cash, Cash Equivalents and Short-Term Investments - Schedule of Breakdown of the Short-Term Investments (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Less than 12 months
Fair Value	$ 97.5	$ 43.5
Gross Unrealized Losses	(0.6)	(0.2)
More than 12 months
Fair Value	396.6	534.8
Gross Unrealized Losses	(18.1)	(21.1)
Total
Fair Value	494.1	578.3
Gross Unrealized Losses	(18.7)	(21.3)
Corporate notes and obligations
Less than 12 months
Fair Value	57.2	25.1
Gross Unrealized Losses	(0.2)	(0.1)
More than 12 months
Fair Value	197.2	240.3
Gross Unrealized Losses	(8.9)	(10.2)
Total
Fair Value	254.4	265.4
Gross Unrealized Losses	(9.1)	(10.3)
U.S. Treasury securities
Less than 12 months
Fair Value	38.7	17.8
Gross Unrealized Losses	(0.4)	(0.1)
More than 12 months
Fair Value	96.4	174.0
Gross Unrealized Losses	(5.2)	(6.0)
Total
Fair Value	135.1	191.8
Gross Unrealized Losses	(5.6)	(6.1)
Asset backed securities
Less than 12 months
Fair Value	1.6	0.6
Gross Unrealized Losses	0.0	0.0
More than 12 months
Fair Value	55.2	66.0
Gross Unrealized Losses	(1.8)	(2.3)
Total
Fair Value	56.8	66.6
Gross Unrealized Losses	(1.8)	(2.3)
Municipal securities
Less than 12 months
Fair Value	0.0	0.0
Gross Unrealized Losses	0.0	0.0
More than 12 months
Fair Value	40.9	46.1
Gross Unrealized Losses	(1.7)	(2.0)
Total
Fair Value	40.9	46.1
Gross Unrealized Losses	(1.7)	(2.0)
U.S. agency obligations
Less than 12 months
Fair Value	0.0	0.0
Gross Unrealized Losses	0.0	0.0
More than 12 months
Fair Value	3.5	3.5
Gross Unrealized Losses	(0.3)	(0.3)
Total
Fair Value	3.5	3.5
Gross Unrealized Losses	(0.3)	(0.3)
Foreign government obligations
Less than 12 months
Fair Value	0.0	0.0
Gross Unrealized Losses	0.0	0.0
More than 12 months
Fair Value	1.8	3.3
Gross Unrealized Losses	(0.1)	(0.2)
Total
Fair Value	1.8	3.3
Gross Unrealized Losses	(0.1)	(0.2)
Supranational securities
Less than 12 months
Fair Value	0.0	0.0
Gross Unrealized Losses	0.0	0.0
More than 12 months
Fair Value	1.6	1.6
Gross Unrealized Losses	(0.1)	(0.1)
Total
Fair Value	1.6	1.6
Gross Unrealized Losses	$ (0.1)	$ (0.1)

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions

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