MARKETABLE SECURITIES - Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Amortized Cost
Less than one year	$ 36.5
One to five years	67.5
Six to ten years	49.7
Greater than ten years	70.3
Amortized Cost	224.0	$ 213.1
Fair Value
Less than one year	36.5
One to five years	69.4
Six to ten years	51.4
Greater than ten years	73.6
Fair Value	$ 230.9	$ 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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