Presentation and Summary of Significant Accounting Policies - Diluted Earnings per Share for Class B Common Shares Using Two-Class Method (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted average common shares (in shares)		33,761	33,365	32,559
Diluted EPS for Common Shares (in shares)		33,992	34,305	33,169
Basic EPS (in usd per share)	[1]	$ 0.31	$ 0.38	$ 0.25
Diluted EPS (in usd per share)		$ 0.31	$ 0.37	$ 0.24
Class B Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed and distributed earnings, Per basic		$ 561	$ 697	$ 452
Reallocation of undistributed earnings from Class A Common Shares to Class B Common Shares		2	4	5
Net earnings		$ 563	$ 701	$ 457
Basic weighted average common shares (in shares)		1,822	1,822	1,822
Diluted EPS for Common Shares (in shares)		1,822	1,822	1,822
Basic EPS (in usd per share)		$ 0.31	$ 0.38	$ 0.25
Diluted EPS (in usd per share)		$ 0.31	$ 0.38	$ 0.25

[1] Diluted per share amounts for Class A shares are shown above. Diluted per share for Class B shares under the two-class method are $0.31, $0.38 and $0.25 for the years ended April 30, 2023, 2022 and 2021, respectively. See Note 1(s) to the Consolidated Financial Statements.