CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Short-term Investments
Cash Equivalents, at Carrying Value	$ 79,933	$ 91,281
Demand Deposits [Member]
Short-term Investments
Cash Equivalents, at Carrying Value	166,100	54,100
Money Market Funds [Member]
Short-term Investments
Cash Equivalents, at Carrying Value	68,956	91,281
US Government Corporations and Agencies Securities [Member]
Short-term Investments
Cash Equivalents, at Carrying Value	$ 10,977	$ 0

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_CashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant