FAIR VALUE MEASUREMENTS - Changes to Level 3 Investment and Transfers (Details) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Changes to the Company's investment classified as Level 3 | ||
| Non-cash settlement of customer receivable | $ 635 | |
| Unrealized gains (losses) related to investment still held | $ (249) | |
| Transfers from level 1 to level 2 | 0 | |
| Transfers between level 1, level 2 or level 3 | 0 | |
| Convertible notes | ||
| Changes to the Company's investment classified as Level 3 | ||
| Balance at beginning of the period | 635 | |
| Non-cash settlement of customer receivable | 635 | |
| Unrealized gains (losses) included in accumulated other comprehensive income | 43 | |
| Transfer out of level 3 due to conversion of convertible notes to common stock | $ (678) | |
| Balance at end of the period | $ 635 | |