Presentation and Summary of Significant Accounting Policies - Basic Earnings per Common Share (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, Basic, by Common Class, Including Two Class Method [Line Items]
Total (in usd per share)	[1]	$ 0.31	$ 0.38	$ 0.25
Basic weighted average common shares (in shares)		33,761	33,365	32,559
Class A Common Shares
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributed earnings per share (in usd per share)		$ 0.44	$ 0.44	$ 0.44
Undistributed (loss) per share (in usd per share)		(0.13)	(0.06)	(0.19)
Total (in usd per share)		$ 0.31	$ 0.38	$ 0.25
Distributed earnings		$ 14,098	$ 13,925	$ 13,556
Undistributed loss		(4,239)	(1,840)	(5,921)
Total		$ 9,859	$ 12,085	$ 7,635
Basic weighted average common shares (in shares)		31,939	31,543	30,737
Class B Common Shares
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributed earnings per share (in usd per share)		$ 0.44	$ 0.44	$ 0.44
Undistributed (loss) per share (in usd per share)		(0.13)	(0.06)	(0.19)
Total (in usd per share)		$ 0.31	$ 0.38	$ 0.25
Distributed earnings		$ 803	$ 803	$ 803
Undistributed loss		(242)	(106)	(351)
Total		$ 561	$ 697	$ 452
Basic weighted average common shares (in shares)		1,822	1,822	1,822

[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.