Financial Instruments - Summary of Contractual Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Estimated Fair Value
Due in one year or less	$ 1,541.1	$ 1,278.9
Due after one year through five years	868.2	722.6
Due after five years	23.8	49.5
Total marketable debt securities	2,433.1	2,051.0
Amortized Cost
Due in one year or less	1,541.7	1,278.6
Due after one year through five years	870.2	721.3
Due after five years	24.0	49.2
Amortized Cost	$ 2,435.9	$ 2,049.1