MARKETABLE SECURITIES - Contractual Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost
Less than one year	$ 32.2
One to five years	60.5
Six to ten years	35.7
Greater than ten years	86.1
Amortized Cost	214.5	$ 213.1
Fair Value
Less than one year	32.2
One to five years	61.4
Six to ten years	36.8
Greater than ten years	89.0
Total Debt Securities	$ 219.4	$ 224.2