MARKETABLE SECURITIES - Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Amortized Cost
Less than one year	$ 51.0
One to five years	44.7
Six to ten years	41.0
Greater than ten years	82.3
Amortized Cost	219.0	$ 228.4
Fair Value
Less than one year	51.0
One to five years	46.5
Six to ten years	43.3
Greater than ten years	87.6
Fair Value	$ 228.4	$ 234.1

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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