Balance Sheet Components (Inventories, Property and Equipment) (Details) - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Inventories    
Finished goods $ 27,455 $ 24,138
Component parts 3,424 1,880
Work-in-process 148 213
Total inventories 31,027 26,231
Property and equipment, net    
Property and equipment, gross 21,569 19,165
Less: accumulated depreciation (14,693) (12,702)
Property and equipment, net 6,876 6,463
Computer equipment and software    
Property and equipment, net    
Property and equipment, gross 4,589 3,855
Manufacturing tooling and test equipment    
Property and equipment, net    
Property and equipment, gross 4,655 4,216
Lab and warehouse equipment    
Property and equipment, net    
Property and equipment, gross 4,124 3,649
Leasehold improvements    
Property and equipment, net    
Property and equipment, gross 3,731 3,438
Furniture and fixtures    
Property and equipment, net    
Property and equipment, gross 3,614 3,254
Other    
Property and equipment, net    
Property and equipment, gross $ 856 $ 753