Financial Instruments (Details 2) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Summary of Contractual Maturities: Available-for-Sale Securities
Due in one year or less, amortized cost	$ 2,151.3	$ 1,541.1
Due in one year or less, estimated fair value	2,135.6	1,541.7
Due after one year through five years, amortized cost	1,089.4	868.2
Due after one year through five years, estimated fair value	1,130.1	870.2
Due after five years, amortized cost	13.5	23.8
Due after five years, estimated fair value	13.9	24.0
Estimated Fair Value	3,254.2	2,433.1
Amortized Cost	$ 3,279.6	$ 2,435.9