NET LOSS PER SHARE - Reconciliation of basic and diluted net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] | |||||||||||
| Net loss | $ (4,845) | $ (1,536) | $ (1,266) | $ (1,285) | $ (3,633) | $ (846) | $ (288) | $ (1,805) | $ (8,932) | $ (6,572) | $ (7,891) |
| Accretion of cumulative dividends of redeemable preferred stock to redemption value | (4,563) | (5,876) | (4,797) | ||||||||
| Forfeiture of 50% of Series B Preferred Stock accumulated dividends | 54,997 | ||||||||||
| Series A Preferred Stock preference payment in common stock | $ (16,000) | $ 0 | $ 0 | ||||||||
| Weighted average number of shares - basic and diluted (in shares) | 4,017,330 | 1,744,356 | 1,744,356 | ||||||||
| Net loss per share attributable to common stockholders - basic and diluted (in dollars per share) | $ (1.41) | $ (1.70) | $ (1.56) | $ (1.55) | $ (3.03) | $ (1.38) | $ (0.97) | $ (1.76) | $ (5.86) | $ (7.14) | $ (7.27) |
| Net loss attributable to common stockholders - basic and diluted | $ (15,078) | $ (3,021) | $ (2,720) | $ (2,711) | $ (5,289) | $ (2,405) | $ (1,688) | $ (3,066) | $ (23,530) | $ (12,448) | $ (12,688) |
| Series B | |||||||||||
| Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] | |||||||||||
| Forfeiture of 50% of Series B Preferred Stock accumulated dividends | $ 5,965 | $ 0 | $ 0 | ||||||||