| BALANCE SHEET COMPONENTS | BALANCE SHEET COMPONENTS 
 The components of certain balance sheet amounts are as follows (in thousands): 
|  |  
|  |  |  |  |  |  |  |  |  
|   | September 30, 2019 |   | December 31, 2018 |  
| Cash, cash equivalents and restricted cash: |   |   |   |  
| Cash | $ | 17,711 | 
 |   | $ | 47,323 | 
 |  
| Cash equivalents | 83,402 | 
 |   | 85,330 | 
 |  
|   | 101,113 | 
 |   | 132,653 | 
 |  
| Restricted cash | 2,881 | 
 |   | 2,998 | 
 |  
|   | $ | 103,994 | 
 |   | $ | 135,651 | 
 |  
| Inventories: |   |   |   |  
| Finished goods | $ | 7,817 | 
 |   | $ | 11,171 | 
 |  
| Raw materials | 1,104 | 
 |   | 1,145 | 
 |  
| Reserve for obsolescence | (922 | ) |   | (151 | ) |  
|   | $ | 7,999 | 
 |   | $ | 12,165 | 
 |  
| Other accrued expenses: |   |   |   |  
| Sales returns | $ | 290 | 
 |   | $ | 801 | 
 |  
| Employee-related expense | 1,998 | 
 |   | 4,051 | 
 |  
| Warehousing, inventory-related and other | 1,104 | 
 |   | 1,269 | 
 |  
|   | $ | 3,392 | 
 |   | $ | 6,121 | 
 |  
| Deferred revenue: |   |   |   |  
| Unshipped product | $ | 1,171 | 
 |   | $ | 4,574 | 
 |  
| Auto ship advances | 1,983 | 
 |   | 1,876 | 
 |  
| Other | 148 | 
 |   | 345 | 
 |  
|   | $ | 3,302 | 
 |   | $ | 6,795 | 
 | 
 |