v3.25.2
Fair Value Measurements (Tables)
 6 Months Ended
Jun. 30, 2025
Fair Value Disclosures [Abstract]  
Schedule of Fair Value Hierarchy for Financial Assets
The following table summarizes financial assets that we measured at fair value on a recurring basis as of June 30, 2025, classified in accordance with the fair value hierarchy:
Fair Value Measurements Using
(In millions)Level 1Level 2Level 3Total
Cash equivalents$560.1 $49.8 $— $609.9 
Debt securities, available-for-sale:
U.S. government agencies (1)
— 945.3 — 945.3 
Commercial paper— 143.7 — 143.7 
Corporate debt— 680.3 — 680.3 
Total debt securities, available-for-sale— 1,769.3 — 1,769.3 
Other long-term assets:
Convertible notes receivable— — 11.1 11.1 
Other assets (2)
19.7 — — 19.7 
Total assets measured at fair value on a recurring basis$579.8 $1,819.1 $11.1 $2,410.0 
(1)Includes debt obligations issued by U.S. government-sponsored enterprises or U.S. government agencies.
(2)Includes assets which are primarily held pursuant to a deferred compensation plan for senior management, which consist mainly of mutual funds.
The following table summarizes financial assets that we measured at fair value on a recurring basis as of December 31, 2024, classified in accordance with the fair value hierarchy:
Fair Value Measurements Using
(In millions)Level 1Level 2Level 3Total
Cash equivalents$134.2 $— $— $134.2 
Debt securities, available-for-sale:
U.S. government agencies (1)
— 1,150.1 — 1,150.1 
Commercial paper— 312.1 — 312.1 
Corporate debt— 511.1 — 511.1 
Total debt securities, available-for-sale— 1,973.3 — 1,973.3 
Other long-term assets:
Convertible notes receivable— — 10.5 10.5 
Other assets (2)
20.6 — — 20.6 
Total assets measured at fair value on a recurring basis$154.8 $1,973.3 $10.5 $2,138.6 
(1)Includes debt obligations issued by U.S. government-sponsored enterprises or U.S. government agencies.
(2)Includes assets which are held pursuant to a deferred compensation plan for senior management, which consist mainly of mutual funds.
Schedule of Estimated Fair Values of Debt Instruments
The fair value, based on trading prices (Level 1 inputs), of our senior convertible notes were as follows as of the dates indicated:
Fair Value Measurements Using Level 1
(In millions)June 30, 2025December 31, 2024
Senior Convertible Notes due 2025$1,187.2 $1,163.7 
Senior Convertible Notes due 20281,175.4 1,122.3 
Total fair value of outstanding senior convertible notes$2,362.6 $2,286.0 
The carrying amounts of our senior convertible notes were as follows as of the dates indicated:
(In millions)June 30, 2025December 31, 2024
Principal amount:
Senior Convertible Notes due 2025$1,207.5 $1,207.5 
Senior Convertible Notes due 20281,250.0 1,250.0 
Total principal amount2,457.5 2,457.5 
Unamortized debt issuance costs(12.5)(16.1)
Carrying amount of senior convertible notes$2,445.0 $2,441.4