Financial Information by Geographic Location (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Jan. 31, 2017 |
Jan. 31, 2016 |
Jan. 31, 2017 |
Jan. 31, 2016 |
|
| Revenues from External Customers and Long-Lived Assets [Line Items] | ||||
| Revenues by geographic location | $ 3,492,000 | $ 6,603,000 | $ 13,086,000 | $ 19,992,000 |
| United States | ||||
| Revenues from External Customers and Long-Lived Assets [Line Items] | ||||
| Revenues by geographic location | 2,363,000 | 5,039,000 | 9,057,000 | 16,260,000 |
| Europe | ||||
| Revenues from External Customers and Long-Lived Assets [Line Items] | ||||
| Revenues by geographic location | 756,000 | 1,396,000 | 2,739,000 | 3,391,000 |
| Other (principally Asia Pacific Region) | ||||
| Revenues from External Customers and Long-Lived Assets [Line Items] | ||||
| Revenues by geographic location | $ 373,000 | $ 168,000 | $ 1,290,000 | $ 341,000 |