Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands |
1 Months Ended | 3 Months Ended | 11 Months Ended | ||
|---|---|---|---|---|---|
Mar. 04, 2019 |
Jan. 31, 2018 |
Apr. 30, 2019 |
Apr. 30, 2018 |
Dec. 31, 2017 |
|
| Income Tax Disclosure [Abstract] | |||||
| Income tax expense (benefit) | $ 402 | $ (494) | |||
| Corporate federal income tax rate | 21.00% | 35.00% | |||
| Preferred shares purchase rights, declared date as dividend | Mar. 04, 2019 | ||||
| Preferred shares purchase rights for each common stock | 1 | ||||
| Preferred shares purchase rights, record date as dividend | Mar. 15, 2019 | ||||