SHARE-BASED COMPENSATION - RSUs with Market Conditions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands |
3 Months Ended | 6 Months Ended | 12 Months Ended | |
|---|---|---|---|---|
Jun. 30, 2018 |
Mar. 31, 2018 |
Jun. 30, 2019 |
Dec. 31, 2018 |
|
| Share-based Compensation Restricted Stock Units With Market Conditions [Line Items] | ||||
| RSUs issued | 1,648 | |||
| Reconciliation Of RSUs With Market Conditions [Abstract] | ||||
| RSUs beginning | 3,685 | |||
| Number of RSUs granted | 1,648 | |||
| Number of RSUs forfeited | (280) | |||
| Number of RSUs vested | (1,367) | |||
| RSUs ending | 3,686 | 3,685 | ||
| Net RSUs increase (decrease) to APIC | $ 3,740 | $ 3,913 | ||
| Restricted Stock Units With Market Conditions [Member] | ||||
| Share-based Compensation Restricted Stock Units With Market Conditions [Line Items] | ||||
| RSUs issued | 0 | 0 | ||
| Reconciliation Of RSUs With Market Conditions [Abstract] | ||||
| RSUs beginning | 650 | 226 | 650 | |
| Number of RSUs granted | 0 | 0 | ||
| Number of RSUs forfeited | (156) | (110) | ||
| Number of RSUs vested | 0 | (314) | ||
| RSUs ending | 70 | 226 | ||
| Fair value of each RSU issued with market conditions | $ 0 | $ 0 | ||