Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
Apr. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Employment agreements	The Company has a policy of entering into offer letters of employment or letters of promotion with vice presidents, which provide for an annual base salary and discretionary and incentive bonus payments. Certain key vice presidents who typically have been employed by the Company for several years may also have a standard form employment agreement. Upon termination without cause, the Company is required to pay the amount of severance due under the employment agreement, if any. The Company also requires its vice presidents to agree in their employment letters and their employment agreement, if applicable, not to compete with the Company during the term of their employment and for a certain period after their employment ends.

Commitments and Contingencies - Additional Information (Detail)

12 Months Ended

Apr. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

The Company has a policy of entering into offer letters of employment or letters of promotion with vice presidents, which provide for an annual base salary and discretionary and incentive bonus payments. Certain key vice presidents who typically have been employed by the Company for several years may also have a standard form employment agreement. Upon termination without cause, the Company is required to pay the amount of severance due under the employment agreement, if any. The Company also requires its vice presidents to agree in their employment letters and their employment agreement, if applicable, not to compete with the Company during the term of their employment and for a certain period after their employment ends.