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, 2022	Apr. 30, 2021	Apr. 30, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total (in usd per share)	[1]	$ 0.38	$ 0.25	$ 0.21
Basic weighted average common shares (in shares)		33,365	32,559	31,747
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 earnings/(loss) per share (in usd per share)		(0.06)	(0.19)	(0.23)
Total (in usd per share)		$ 0.38	$ 0.25	$ 0.21
Distributed earnings		$ 13,925	$ 13,556	$ 13,219
Undistributed earnings/(loss)		(1,840)	(5,921)	(6,864)
Total		$ 12,085	$ 7,635	$ 6,355
Basic weighted average common shares (in shares)		31,543	30,737	29,925
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 earnings/(loss) per share (in usd per share)		(0.06)	(0.19)	(0.23)
Total (in usd per share)		$ 0.38	$ 0.25	$ 0.21
Distributed earnings		$ 803	$ 803	$ 805
Undistributed earnings/(loss)		(106)	(351)	(418)
Total		$ 697	$ 452	$ 387
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 $0.38, $0.25 and $0.22 for the years ended April 30, 2022, 2021 and 2020, respectively. See Note 1 to the Consolidated Financial Statements.