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
		Jul. 31, 2020	Jul. 31, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic weighted aveage common shares outstanding (in shares)		32,339	31,270
Diluted, Class A Common Shares (in shares)		32,932	31,951
Basic EPS (in usd per share)	[1]	$ 0.06	$ 0.04
Diluted EPS (in usd per share)	[1]	$ 0.06	$ 0.04
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & distributed earnings		$ 1,920	$ 1,082
Undistributed & distributed earnings, class B conversion (in usd per share)		114	70
Net earnings		$ 2,034	$ 1,152
Basic weighted aveage common shares outstanding (in shares)		30,517	29,448
Common Stock Equivalents (in shares)		593	681
Weighted average shares including common stock equivalents, diluted (in shares)		31,110	30,129
Class B Conversion (in shares)		1,822	1,822
Diluted, Class A Common Shares (in shares)		32,932	31,951
Basic EPS (in usd per share)		$ 0.06	$ 0.04
Diluted EPS (in usd per share)		$ 0.06	$ 0.04

[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 $0.06 and $0.04 for the three months ended July 31, 2020 and 2019. See Note E to the Condensed Consolidated Financial Statements.