NET INCOME (LOSS) PER COMMON SHARE - Antidilutive Securities (Details) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded shares as anti-dilutive when reporting a net loss	139	331	755
Price range of option: from (in dollars per share)	$ 0.17
Price range of option: to (in dollars per share)	$ 13.98
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded shares as anti-dilutive when reporting a net loss	609	543	564
Price range of option: from (in dollars per share)	$ 3.54	$ 9.66	$ 6.43
Price range of option: to (in dollars per share)	$ 13.98	$ 13.98	$ 13.98
RSUs \| Restricted Stock Units Service Conditions
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded shares as anti-dilutive when reporting a net loss	2,689	2,953	1,394
RSUs \| Restricted Stock Units Service And Market Conditions But Market Not Met
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded shares as anti-dilutive when reporting a net loss	0	70	226

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://www.xbrl.org/2003/role/disclosureRef
-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

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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