FAIR VALUE MEASUREMENT (Narrative) (Details) $ in Millions	Mar. 31, 2019 USD ($)
Seven Point Five Percentage Convertible Notes 2021 [Member]
Debt Instrument, Interest Rate, Stated Percentage	7.50%
Fair Value, Inputs, Level 3 [Member] \| Seven Point Five Percentage Convertible Notes [Member]
Convertible Debt, Fair Value Disclosures	$ 64.5
Debt Instrument, Face Amount	$ 57.9

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant