INVESTMENTS (Details 2) $ in Millions	Dec. 31, 2015 USD ($)
Available-for-sale securities by contractual maturity
Due within one year, Cost	$ 546.2
Due after one through five years, Cost	712.7
Cost, Total	1,258.9
Due within one year, Fair Value	546.1
Due after one through five years, Fair Value	709.3
Fair Value, Total	$ 1,255.4