FAIR VALUE OF FINANCIAL INSTRUMENTS - Schedule of Financial Instruments (Details)
$ in Thousands |
Jun. 30, 2019
USD ($)
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
$ 102,910
|
| Fair Value |
103,303
|
| Fair Value, Measurements, Recurring |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
102,910
|
| Gross Unrealized Gains |
396
|
| Gross Unrealized Losses |
(3)
|
| Fair Value |
103,303
|
| Cash and Cash Equivalents |
1,852
|
| Short-Term Investments |
69,866
|
| Long-Term Investments |
31,585
|
| Fair Value, Measurements, Recurring | Level 1 |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
1,328
|
| Gross Unrealized Gains |
0
|
| Gross Unrealized Losses |
0
|
| Fair Value |
1,328
|
| Cash and Cash Equivalents |
1,328
|
| Short-Term Investments |
0
|
| Long-Term Investments |
0
|
| Fair Value, Measurements, Recurring | Level 1 | Money market funds |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
1,328
|
| Gross Unrealized Gains |
0
|
| Gross Unrealized Losses |
0
|
| Fair Value |
1,328
|
| Cash and Cash Equivalents |
1,328
|
| Short-Term Investments |
0
|
| Long-Term Investments |
0
|
| Fair Value, Measurements, Recurring | Level 2 |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
101,582
|
| Gross Unrealized Gains |
396
|
| Gross Unrealized Losses |
(3)
|
| Fair Value |
101,975
|
| Cash and Cash Equivalents |
524
|
| Short-Term Investments |
69,866
|
| Long-Term Investments |
31,585
|
| Fair Value, Measurements, Recurring | Level 2 | Commercial paper |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
1,123
|
| Gross Unrealized Gains |
0
|
| Gross Unrealized Losses |
0
|
| Fair Value |
1,123
|
| Cash and Cash Equivalents |
524
|
| Short-Term Investments |
599
|
| Long-Term Investments |
0
|
| Fair Value, Measurements, Recurring | Level 2 | Corporate securities |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
83,568
|
| Gross Unrealized Gains |
372
|
| Gross Unrealized Losses |
(2)
|
| Fair Value |
83,938
|
| Cash and Cash Equivalents |
0
|
| Short-Term Investments |
57,377
|
| Long-Term Investments |
26,561
|
| Fair Value, Measurements, Recurring | Level 2 | U.S agency securities |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
4,702
|
| Gross Unrealized Gains |
4
|
| Gross Unrealized Losses |
0
|
| Fair Value |
4,706
|
| Cash and Cash Equivalents |
0
|
| Short-Term Investments |
3,712
|
| Long-Term Investments |
994
|
| Fair Value, Measurements, Recurring | Level 2 | US Government Bonds |
|
| Marketable Securities [Line Items] |
|
| Adjusted cost |
12,189
|
| Gross Unrealized Gains |
20
|
| Gross Unrealized Losses |
(1)
|
| Fair Value |
12,208
|
| Cash and Cash Equivalents |
0
|
| Short-Term Investments |
8,178
|
| Long-Term Investments |
$ 4,030
|