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		6 Months Ended
		Oct. 31, 2022	Oct. 31, 2021	Oct. 31, 2022	Oct. 31, 2021
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted average common shares outstanding (in shares)		33,720	33,337	33,688	33,195
Diluted EPS for class B common shares (in shares)		34,071	34,685	34,040	34,448
Basic EPS (in usd per share)	[1]	$ 0.06	$ 0.10	$ 0.12	$ 0.19
Class B Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed and distributed earnings		$ 112	$ 181	$ 228	$ 342
Reallocation of undistributed earnings/losses from Class A Common Shares to Class B Common Shares		1	1	2	2
Net earnings		$ 113	$ 182	$ 230	$ 344
Basic weighted average common shares outstanding (in shares)		1,822	1,822	1,822	1,822
Diluted EPS for class B common shares (in shares)		1,822	1,822	1,822	1,822
Basic EPS (in usd per share)		$ 0.06	$ 0.10	$ 0.12	$ 0.19
Diluted EPS (in usd per share)		$ 0.06	$ 0.10	$ 0.12	$ 0.19

[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 $0.06 and $0.10 for the three months ended October 31, 2022 and 2021 and $0.12 and $0.19 for the six months ended October 31, 2022 and 2021. See Note D to the Condensed Consolidated Financial Statements.