| Supplemental Balance Sheet Disclosures [Text Block] | BALANCE SHEET COMPONENTS 
 The components of certain balance sheet amounts are as follows (in thousands): 
|  |  
|  |  |  |  |  |  |  |  |  
|   | March 31, 2018 |   | December 31, 2017 |  
| Cash, cash equivalents and restricted cash: |   |   |   |  
| Cash | $ | 70,249 | 
 |   | $ | 61,703 | 
 |  
| Cash equivalents | 74,846 | 
 |   | 73,608 | 
 |  
|   | 145,095 | 
 |   | 135,311 | 
 |  
| Restricted cash | 3,279 | 
 |   | 3,167 | 
 |  
|   | $ | 148,374 | 
 |   | $ | 138,478 | 
 |  
| Inventories: |   |   |   |  
| Finished goods | $ | 7,524 | 
 |   | $ | 7,779 | 
 |  
| Raw materials | 572 | 
 |   | 799 | 
 |  
| Inventory reserve for obsolescence | (152 | ) |   | (180 | ) |  
|   | $ | 7,944 | 
 |   | $ | 8,398 | 
 |  
| Other accrued expenses: |   |   |   |  
| Sales returns | $ | 689 | 
 |   | $ | 614 | 
 |  
| Employee-related expense | 5,316 | 
 |   | 5,568 | 
 |  
| Warehousing, inventory-related and other | 2,544 | 
 |   | 1,423 | 
 |  
|   | $ | 8,549 | 
 |   | $ | 7,605 | 
 |  
| Deferred revenue: |   |   |   |  
| Unshipped product | $ | 2,017 | 
 |   | $ | 2,411 | 
 |  
| Auto ship advances | 1,740 | 
 |   | 1,665 | 
 |  
| Other | 355 | 
 |   | 379 | 
 |  
|   | $ | 4,112 | 
 |   | $ | 4,455 | 
 |  |