FAIR VALUE DISCLOSURES - Financial instruments measured at fair value on non-recurring basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets:
Assets held for sale	$ 692	$ 4,032
Fair value on a non-recurring basis
Assets:
Assets held for sale	692	4,032
Fair value on a non-recurring basis \| Level 2
Assets:
Assets held for sale	$ 692	$ 4,032

Amount of assets held-for-sale that are not part of a disposal group, expected to be sold within a year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 15
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=123398962&loc=d3e400-110220

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