v3.24.3
Fair Value Measurements (Tables)
 9 Months Ended
Sep. 30, 2024
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 September 30, 2024, classified in accordance with the fair value hierarchy:
Fair Value Measurements Using
(In millions)Level 1Level 2Level 3Total
Cash equivalents$315.4 $— $— $315.4 
Debt securities, available-for-sale:
U.S. government agencies (1)
— 1,038.1 — 1,038.1 
Commercial paper— 391.1 — 391.1 
Corporate debt— 441.9 — 441.9 
Total debt securities, available-for-sale— 1,871.1 — 1,871.1 
Other assets (2)
21.2 — — 21.2 
Total assets measured at fair value on a recurring basis$336.6 $1,871.1 $— $2,207.7 
(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, 2023, classified in accordance with the fair value hierarchy:
Fair Value Measurements Using
(In millions)Level 1Level 2Level 3Total
Cash equivalents$315.9 $— $— $315.9 
Debt securities, available-for-sale:
U.S. government agencies (1)
— 1,612.5 — 1,612.5 
Commercial paper— 184.7 — 184.7 
Corporate debt— 360.6 — 360.6 
Total debt securities, available-for-sale— 2,157.8 — 2,157.8 
Other assets (2)
15.2 — — 15.2 
Total assets measured at fair value on a recurring basis$331.1 $2,157.8 $— $2,488.9 
(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:
(In millions)September 30, 2024December 31, 2023
Senior Convertible Notes due 2025$1,152.3 $1,262.8 
Senior Convertible Notes due 20281,107.1 1,281.8 
Total fair value of outstanding senior convertible notes$2,259.4 $2,544.6 
The carrying amounts of our senior convertible notes were as follows as of the dates indicated:
(In millions)September 30, 2024December 31, 2023
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(17.9)(23.3)
Carrying amount of senior convertible notes$2,439.6 $2,434.2