EARNINGS PER COMMON SHARE - Anti-dilutive Securities (Details) - shares	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
EARNINGS PER COMMON SHARE
Total potentially dilutive securities	326,313	567,788
Stock options
EARNINGS PER COMMON SHARE
Total potentially dilutive securities	278,109	419,197
Time Vesting Units
EARNINGS PER COMMON SHARE
Total potentially dilutive securities	3,982	86,923
Financial Performance Units
EARNINGS PER COMMON SHARE
Total potentially dilutive securities	23,168
Restricted Stock Awards
EARNINGS PER COMMON SHARE
Total potentially dilutive securities	21,054	61,668

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration