FAIR VALUE MEASUREMENTS - Changes to Level 3 Investment and Transfers (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Changes to the Company's investment classified as Level 3 | ||||||
| Transfers from level 1 to level 2 | $ 7,984 | $ 7,984 | ||||
| Transfers between level 1, level 2 or level 3 | $ 0 | $ 0 | ||||
| Convertible notes | ||||||
| Changes to the Company's investment classified as Level 3 | ||||||
| Balance at beginning of the period | 678 | $ 657 | $ 635 | $ 635 | ||
| Unrealized gains (losses) included in accumulated other comprehensive income | 21 | 22 | ||||
| Transfer out of level 3 due to conversion of convertible notes to common stock | $ (678) | |||||
| Balance at end of the period | $ 678 | $ 657 | ||||