INVESTMENTS - Contractual Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Amortized Cost
Due in one year or less			$ 6.8
Due after one year through five years			102.8
Due five years through 10 years			6.2
Due after 10 years			16.8
Total	$ 132.6	$ 218.4
Fair Value
Due in one year or less			6.9
Due after one year through five years			104.5
Due five years through 10 years			6.2
Due after 10 years			$ 17.1
Total investments	$ 134.7	$ 224.0