FAIR VALUE MEASUREMENT (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Jul. 24, 2017	Jun. 24, 2017	Dec. 02, 2016
Four Point Five Percentage Convertible Notes [Member]
Debt Instrument, Face Amount		$ 9.0	$ 9.0
Seven Point Five Percentage Convertible Notes [Member]
Debt Instrument, Face Amount			$ 10.0	$ 22.5
Seven Point Five Percentage Convertible Notes 2016 [Member]
Debt Instrument, Face Amount		$ 10.0
Fair Value, Inputs, Level 3 [Member] | Four Point Five Percentage Convertible Notes [Member]
Convertible Debt, Fair Value Disclosures	$ 5.7
Fair Value, Inputs, Level 3 [Member] | Seven Point Five Percentage Convertible Notes [Member]
Convertible Debt, Fair Value Disclosures	76.6
Fair Value, Inputs, Level 3 [Member] | Four Point Five Percentage Convertible Notes 2013 [Member]
Debt Instrument, Face Amount	5.9
Fair Value, Inputs, Level 3 [Member] | Seven Point Five Percentage Convertible Notes 2016 [Member]
Debt Instrument, Face Amount	$ 59.1