Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Option to purchase common stock (in shares)			1,093,000	1,201,000
Stock-based compensation expense	$ 600	$ 500	$ 1,510	$ 1,308
Income tax excess benefit	141	$ 26	$ 614	$ 260
Stock options exercised (in shares)			802,444	456,113
Total intrinsic value of options exercised			$ 4,100	$ 2,100
Unrecognized compensation cost related to unvested stock option	$ 6,100		$ 6,100
Weighted average period for unrecognized compensation cost			1 year 10 months 28 days