INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost, as adjusted	$ 20,573	$ 27,999
Gross unrealized holding gains	0	0
Gross unrealized holding losses	17	35
Estimated fair value	20,556	27,964
Short-term Investments [Member] \| US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost, as adjusted	20,573	27,999
Gross unrealized holding gains	0	0
Gross unrealized holding losses	17	35
Estimated fair value	$ 20,556	$ 27,964

Amount of investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

+ Details

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

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrealized holding gain before loss recognized in the income statement for investments in trading securities.

+ References

No definition available.

+ Details

Name:	us-gaap_TradingSecuritiesUnrealizedHoldingGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of unrealized holding loss before gain recognized in the income statement for investments in trading securities.

+ References

No definition available.

+ Details

Name:	us-gaap_TradingSecuritiesUnrealizedHoldingLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InformationByCategoryOfDebtSecurityAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: