LEASES - Components of lease cost (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)
LEASES
Amortization of ROU asset	$ 24
Interest on lease liabilities	20
Operating lease cost	3,464
Variable lease cost	467
Short-term lease cost	713
Sublease income	(1,461)
Total	$ 3,227

Amount of interest expense on finance lease liability.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
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-Section 55
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-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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- References

No definition available.

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	debit
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- Definition

Amount of short-term lease cost, excluding expense for lease with term of one month or less.

+ References

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

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Balance Type:	credit
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- Definition

Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

+ References

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