Stockholders' Equity - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Stock-based compensation expense | ||
| Stock-based compensation expense | $ 586 | $ 810 |
| Cost of goods sold. | ||
| Stock-based compensation expense | ||
| Stock-based compensation expense | 52 | 65 |
| Research and development | ||
| Stock-based compensation expense | ||
| Stock-based compensation expense | 21 | 29 |
| Selling, general and administrative | ||
| Stock-based compensation expense | ||
| Stock-based compensation expense | $ 513 | $ 716 |