Earnings Per Common Share - Diluted Earnings per Share for Class A Common Shares Using If-Converted Method (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted average common shares outstanding (in shares)		32,489	31,609	32,414	31,440
Diluted, Class A Common Shares (in shares)		32,896	32,310	32,919	32,066
Basic EPS (in usd per share)	[1]	$ 0.02	$ 0.06	$ 0.08	$ 0.09
Diluted EPS (in usd per share)	[1]	$ 0.02	$ 0.05	$ 0.08	$ 0.09
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & distributed earnings		$ 653	$ 1,658	$ 2,573	$ 2,742
Undistributed & distributed earnings, class B conversion (in usd per share)		39	101	153	169
Net earnings		$ 692	$ 1,759	$ 2,726	$ 2,911
Basic weighted average common shares outstanding (in shares)		30,667	29,787	30,592	29,618
Common Stock Equivalents (in shares)		407	701	505	626
Weighted average shares including common stock equivalents, diluted (in shares)		31,074	30,488	31,097	30,244
Class B Conversion (in shares)		1,822	1,822	1,822	1,822
Diluted, Class A Common Shares (in shares)		32,896	32,310	32,919	32,066
Basic EPS (in usd per share)		$ 0.02	$ 0.06	$ 0.08	$ 0.09
Diluted EPS (in usd per share)		$ 0.02	$ 0.05	$ 0.08	$ 0.09

[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 $0.02 and $0.06 for the three months ended October 31, 2020 and 2019 and $0.09 and $0.10 for the six months ended October 31, 2020 and 2019. See Note E to the Condensed Consolidated Financial Statements.