Presentation and Summary of Significant Accounting Policies - Diluted Earnings per Share for Class A Common Shares Using If-Converted Method (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, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic (in shares)		33,365	32,559	31,747
Class A common shares. diluted (in shares)		34,305	33,169	32,367
Basic, EPS (in usd per share)	[1]	$ 0.38	$ 0.25	$ 0.21
Diluted (in usd per share)		$ 0.37	$ 0.24	$ 0.21
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed and distributed earnings, Per basic		$ 12,085	$ 7,635	$ 6,355
Undistributed and distributed earnings, Class B conversion		697	452	387
Net earnings		$ 12,782	$ 8,087	$ 6,742
Basic (in shares)		31,543	30,737	29,925
Common stock equivalents (in shares)		940	610	620
Weighted average number of shares including common stock equivalents, diluted		32,483	31,347	30,545
Class B conversion (in shares)		1,822	1,822	1,822
Class A common shares. diluted (in shares)		34,305	33,169	32,367
Basic, EPS (in usd per share)		$ 0.38	$ 0.25	$ 0.21
Diluted (in usd per share)	[1]	$ 0.37	$ 0.24	$ 0.21

[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.