COMMITMENTS AND CONTINGENCIES, LEASES (Details) - Cambridge Lease $ in Thousands			12 Months Ended
Nov. 01, 2018	Oct. 31, 2017 USD ($) ft² item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Commitments
Lease space (in square feet) \| ft²		26,342
Term of commercial lease	5 years	6 years 3 months
Number of options to extend lease \| item		1
Term of lease extension option		5 years
Standby letter of credit		$ 311
Deferred rent liability			$ 397	$ 276
Leasehold improvements, net			$ 61	$ 143

No definition available.

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- Definition

Amount after accumulated depreciation of additions or improvements to assets held under a lease arrangement.

+ References

No definition available.

+ Details

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- Definition

The number of options the entity has to extend the lease.

+ References

No definition available.

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- Definition

Area of a real estate property.

+ References

No definition available.

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- Definition

The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property by the lessor or lessee, respectively.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e39896-112707

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- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

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Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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