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
		Jul. 31, 2021	Jul. 31, 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted aveage common shares outstanding (in shares)		33,053,000	32,339,000
Diluted, Class A Common Shares (in shares)		33,946,000	32,932,000
Basic EPS (in usd per share)	[1]	$ 0.09	$ 0.06
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & distributed earnings		$ 2,784	$ 1,920
Undistributed & distributed earnings, class B conversion (in usd per share)		163	114
Net earnings		$ 2,947	$ 2,034
Basic weighted aveage common shares outstanding (in shares)		31,231,000	30,517,000
Common Stock Equivalents (in shares)		893,000	593,000
Weighted average shares including common stock equivalents, diluted (in shares)		32,124,000	31,110,000
Class B Conversion (in shares)		1,822,000	1,822,000
Diluted, Class A Common Shares (in shares)		33,946,000	32,932,000
Basic EPS (in usd per share)		$ 0.09	$ 0.06
Diluted EPS (in usd per share)	[1]	$ 0.09	$ 0.06

[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 $0.06 for the three months ended July 31, 2021 and 2020. See Note D to the Condensed Consolidated Financial Statements.