Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Jan. 31, 2018 |
Apr. 30, 2018 |
Apr. 30, 2017 |
Jan. 31, 2018 |
|
| Finite-Lived Intangible Assets [Line Items] | ||||
| Goodwill impairment | $ 1,500,000 | $ 0 | ||
| Aggregate amortization expense | $ 447,000 | $ 355,000 | ||
| Minimum | ||||
| Finite-Lived Intangible Assets [Line Items] | ||||
| Useful life of intangible assets | 5 years | |||
| Maximum | ||||
| Finite-Lived Intangible Assets [Line Items] | ||||
| Useful life of intangible assets | 15 years | |||