Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance, Shares at Apr. 30, 2019		16,849,026
Beginning Balance at Apr. 30, 2019	$ 632,473	$ 352,424	$ 329,540	$ (49,491)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	73,653		73,653
Other comprehensive income (loss), net of tax	(1,682)			(1,682)
Stock-based compensation	3,989	$ 3,989
Exercise of stock-based compensation awards, net of amounts withheld for taxes, shares		31,790
Exercise of stock-based compensation awards, net of amounts withheld for taxes	(755)	$ (755)
Employee benefit plan contributions, shares		45,721
Employee benefit plan contributions	3,772	$ 3,772
Ending Balance, Shares at Apr. 30, 2020		16,926,537
Ending Balance at Apr. 30, 2020	711,450	$ 359,430	403,193	(51,173)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	61,193		61,193
Other comprehensive income (loss), net of tax	(3,395)			(3,395)
Stock-based compensation	4,598	$ 4,598
Exercise of stock-based compensation awards, net of amounts withheld for taxes, shares		29,019
Exercise of stock-based compensation awards, net of amounts withheld for taxes	(1,351)	$ (1,351)
Stock repurchases, shares		(200,046)
Stock repurchases	(20,000)	$ (3,896)	(16,104)
Employee benefit plan contributions, shares		45,591
Employee benefit plan contributions	$ 3,743	$ 3,743
Ending Balance, Shares at Apr. 30, 2021	16,801,101	16,801,101
Ending Balance at Apr. 30, 2021	$ 756,238	$ 362,524	448,282	(54,568)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(29,722)		(29,722)
Other comprehensive income (loss), net of tax	64,793			64,793
Stock-based compensation	4,708	$ 4,708
Exercise of stock-based compensation awards, net of amounts withheld for taxes, shares		29,808
Exercise of stock-based compensation awards, net of amounts withheld for taxes	(1,072)	$ (1,072)
Stock repurchases, shares		(299,781)
Stock repurchases	(25,000)	$ (5,874)	(19,126)
Employee benefit plan contributions, shares		39,491
Employee benefit plan contributions	$ 2,938	$ 2,938
Ending Balance, Shares at Apr. 30, 2022	16,570,619	16,570,619
Ending Balance at Apr. 30, 2022	$ 772,883	$ 363,224	$ 399,434	$ 10,225