Diluted Earnings Per Share for Class A Common Shares Using If-Converted Method (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Jul. 31, 2016	Jul. 31, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & Distributed Earnings, Per Basic		$ 1,688	$ 2,572
Basic weighted average common shares outstanding		28,938	28,614
Diluted, Class A Common Shares		29,254	28,882
Basic, EPS	[1]	$ 0.06	$ 0.09
Diluted, EPS	[1]	$ 0.06	$ 0.09
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & Distributed Earnings, Per Basic		$ 1,550	$ 2,340
Undistributed & Distributed Earnings, Class B Common share Conversion		138	232
Net Income (Loss) Available to Common Stockholders, Diluted, Total		$ 1,688	$ 2,572
Basic weighted average common shares outstanding		26,457	26,027
Common Stock Equivalents		316	268
Weighted Average Number of Shares Including Common Stock Equivalents, Diluted		26,773	26,295
Class B Common Share Conversion		2,481	2,587
Diluted, Class A Common Shares		29,254	28,882
Basic, EPS	[2]	$ 0.06	$ 0.09
Diluted, EPS	[2]	$ 0.06	$ 0.09

[1] Basic per share amounts are the same for Class A and Class B Common Shares. Diluted per share amounts for Class A Common Shares are shown above. Diluted earnings per share for Class B Common Shares under the two-class method are $0.06 and $0.09 for the three months ended July 31, 2016 and 2015, respectively. See Note D to the Condensed Consolidated Financial Statements.

[2] Amounts adjusted for rounding