NOTES PAYABLE TO BANKS - Interest incurred (Details) - Revolving credit facility - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revolving credit facility
Interest incurred	$ 89	$ 103	$ 178	$ 206
Interest paid	$ 58	$ 62	$ 121	$ 133

Total interest costs incurred during the period and either capitalized or charged against earnings.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.8)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

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