INVESTMENTS (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) security	Dec. 31, 2015 USD ($) security	Dec. 31, 2014 USD ($)
INVESTMENTS [Abstract]
Proceeds from sales of available-for-sale investment securities	$ 229.3	$ 157.2	$ 87.1
Debt and equity securities held in an unrealized loss position | security	1,132	676
Debt securities and equity securities held in an unrealized loss position 12 months or more | security	36	22
OTTI losses	$ 0.3	$ 0.4	$ 0.0
Fair value of investments deposited with governmental authorities required by law	$ 7.9