MARKETABLE SECURITIES - Schedule of Contractual Maturities (Details) $ in Millions	Jun. 30, 2017 USD ($)
Amortized Cost
Less than one year	$ 53.0
One to five years	52.6
Six to ten years	54.7
Greater than ten years	130.0
Total Debt Securities	290.3
Fair Value
Less than one year	52.9
One to five years	53.4
Six to ten years	56.3
Greater than ten years	131.9
Total Debt Securities	$ 294.5