Net Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Oct. 31, 2022	Jul. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Oct. 31, 2022	Oct. 31, 2021
Earnings Per Share [Abstract]
Net income	$ 28,784	$ 20,070	$ 2,030	$ 2,981	$ 48,854	$ 5,011
Denominator for basic net earnings per common share - weighted-average shares	16,614,677		16,567,391		16,599,136	16,614,112
Effect of dilutive securities:
Stock options and restricted stock units	42,000		39,000		40,000	49,000
Diluted (in shares)	16,657,454		16,605,911		16,638,741	16,662,791
Earnings Per Share, Basic [Abstract]
Basic (in usd per share)	$ 1.73		$ 0.12		$ 2.94	$ 0.30
Earnings Per Share, Diluted [Abstract]
Diluted (in usd per share)	$ 1.73		$ 0.12		$ 2.94	$ 0.30
Stock excluded from the calculation of net earnings per share (shares)					0	0