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SHARE-BASED COMPENSATION - Restricted Stock Unit Activity (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-Based Compensation Awards
Stock-based compensation expenses	$ 21	$ 0	$ 56	$ 0
Restricted stock units issued and outstanding
Granted (in shares)			10,296
Outstanding and expected to vest at end of period (in shares)	10,296		10,296
Weighted average fair value of units granted in period (in dollars per share)	$ 23.11		$ 23.11
Unrecognized compensation	$ 183		$ 183
Expected vesting period			2 years 3 months 18 days
Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	18		$ 50
General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 2		$ 6