INVESTMENTS - Schedule of Cost and Fair Value of Investments in Debt Securities, by Contractual Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Amortized Cost
Due in 1 year or less	$ 44.7
Due after 1 year through 5 years	0.0
Instruments not due at a single maturity date	0.0
Amortized Cost	44.7
Fair Value
Due in 1 year or less	44.7
Due after 1 year through 5 years	0.0
Instruments not due at a single maturity date	0.0
Fair Value	44.7
Amortized Cost
Due in 1 year or less	745.4
Due after 1 year through 5 years	28.5
Instruments not due at a single maturity date	65.5
Amortized Cost	839.4	$ 1,026.4
Fair Value
Due in 1 year or less	744.7
Due after 1 year through 5 years	28.0
Instruments not due at a single maturity date	64.0
Fair Value	$ 836.7	$ 1,021.3