MARKETABLE SECURITIES - Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Amortized Cost
Less than one year	$ 40.4
One to five years	60.6
Six to ten years	52.4
Greater than ten years	60.9
Amortized Cost	214.3	$ 213.1
Fair Value
Less than one year	40.4
One to five years	62.3
Six to ten years	53.3
Greater than ten years	63.3
Fair Value	$ 219.3	$ 224.2

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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