Net Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jul. 31, 2022	Jul. 31, 2021
Earnings Per Share [Abstract]
Net income (loss)	$ 20,070	$ 2,981
Denominator for basic net earnings per common share - weighted-average shares	16,583,595	16,660,833
Effect of dilutive securities:
Stock options and restricted stock units	36,000	55,000
Diluted (in shares)	16,619,916	16,716,167
Earnings Per Share, Basic [Abstract]
Basic (in usd per share)	$ 1.21	$ 0.18
Earnings Per Share, Diluted [Abstract]
Diluted (in usd per share)	$ 1.21	$ 0.18
Stock excluded from the calculation of net earnings per share (shares)	0	0