Diluted Earnings Per Share for Class A Common Shares Using If-Converted Method (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Oct. 31, 2014		Oct. 31, 2013		Oct. 31, 2014		Oct. 31, 2013
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & Distributed Earnings, Per Basic	$ 1,175		$ 3,693		$ 2,709		$ 5,286
Basic weighted average common shares outstanding	28,270		27,448		28,252		27,406
Diluted, Class A Common Shares	28,586		27,874		28,595		27,841
Basic, EPS	$ 0.04	[1]	$ 0.13	[1]	$ 0.10	[1]	$ 0.19	[1]
Diluted, EPS	$ 0.04	[1]	$ 0.13	[1]	$ 0.10	[1]	$ 0.19	[1]
Class A Common Shares
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed & Distributed Earnings, Per Basic	1,067		3,345		2,461		4,788
Undistributed & Distributed Earnings, Class B Conversion	108		348		248		498
Net Income (Loss) Available to Common Stockholders, Diluted, Total	$ 1,175		$ 3,693		$ 2,709		$ 5,286
Basic weighted average common shares outstanding	25,683		24,861		25,665		24,819
Common Stock Equivalents	316		426		343		435
Weighted Average Number of Shares Including Common Stock Equivalents, Diluted	25,999		25,287		26,008		25,254
Class B Conversion	2,587		2,587		2,587		2,587
Diluted, Class A Common Shares	28,586		27,874		28,595		27,841
Basic, EPS	$ 0.04		$ 0.13		$ 0.10		$ 0.19
Diluted, EPS	$ 0.04		$ 0.13		$ 0.10		$ 0.19

[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 $0.04 and $0.13 for the three months ended October 31, 2014 and 2013 and $0.10 and $0.19 for the six months ended October 31, 2014 and 2013, respectively. See Note D to the Condensed Consolidated Financial Statements.