Earnings Per Common Share - Diluted Earnings per Share for Class B Common Shares Using Two-Class Method (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Jul. 31, 2023	Jul. 31, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted average common shares outstanding (in shares)		34,155	33,656
Diluted EPS for class B common shares (in shares)		34,160	34,007
Basic EPS (in usd per share)	[1]	$ 0.08	$ 0.06
Class B Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed and distributed earnings		$ 146	$ 116
Reallocation of undistributed earnings/losses from Class A Common Shares to Class B Common Shares		0	1
Diluted EPS, Net earnings		$ 146	$ 117
Basic weighted average common shares outstanding (in shares)		1,822	1,822
Diluted EPS for class B common shares (in shares)		1,822	1,822
Basic EPS (in usd per share)		$ 0.08	$ 0.06
Diluted EPS (in usd per share)		$ 0.08	$ 0.06

[1] Basic per share amounts are the same for Class A and Class B shares. Diluted per share amounts for Class A shares are shown above. Diluted earnings per share for Class B shares under the two-class method are $0.08 and $0.06 for the three months ended July 31, 2023 and 2022, respectively. See Note D to the Condensed Consolidated Financial Statements.