Earnings Per Common Share - Diluted Earnings per Share for Class A Common Shares Using If-Converted Method (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted aveage common shares outstanding (in shares)		33,490,000	32,628,000	33,293,000	32,485,000
Diluted, Class A Common Shares (in shares)		34,578,000	33,293,000	34,325,000	33,107,000
Basic EPS (in usd per share)	[1]	$ 0.09	$ 0.07	$ 0.28	$ 0.16
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & distributed earnings		$ 2,780	$ 2,182	$ 8,699	$ 4,755
Undistributed & distributed earnings, class B conversion		160	129	502	282
Net earnings		$ 2,940	$ 2,311	$ 9,201	$ 5,037
Basic weighted aveage common shares outstanding (in shares)		31,668,000	30,806,000	31,471,000	30,663,000
Common Stock Equivalents (in shares)		1,088,000	665,000	1,032,000	622,000
Weighted average shares including common stock equivalents, diluted (in shares)		32,756,000	31,471,000	32,503,000	31,285,000
Class B Conversion (in shares)		1,822,000	1,822,000	1,822,000	1,822,000
Diluted, Class A Common Shares (in shares)		34,578,000	33,293,000	34,325,000	33,107,000
Basic EPS (in usd per share)		$ 0.09	$ 0.07	$ 0.28	$ 0.16
Diluted EPS (in usd per share)	[1]	$ 0.09	$ 0.07	$ 0.27	$ 0.15

[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 $0.09 and $0.07 for the three months ended January 31, 2022 and 2021 and $0.28 and $0.16 for the nine months ended January 31, 2022 and 2021. See Note D to the Condensed Consolidated Financial Statements.