Net Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Jan. 31, 2023	Jan. 31, 2022
Earnings Per Share [Abstract]
Net income (loss)	$ 14,728	$ 28,784	$ 20,070	$ (49,257)	$ 2,030	$ 2,981	$ 63,582	$ (44,246)
Denominator for basic net earnings per common share - weighted-average shares	16,621,827			16,569,881			16,606,700	16,599,369
Effect of dilutive securities:
Stock options and restricted stock units	74,000			0			54,000	0
Diluted (in shares)	16,695,714			16,569,881			16,661,234	16,599,369
Earnings Per Share, Basic [Abstract]
Basic (in usd per share)	$ 0.89			$ (2.97)			$ 3.83	$ (2.67)
Earnings Per Share, Diluted [Abstract]
Diluted (in usd per share)	$ 0.88			$ (2.97)			$ 3.82	$ (2.67)
Stock excluded from the calculation of net earnings per share (shares)	0			40,973			0	47,878