Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning Balance at Apr. 30, 2010	$ 88,153	$ 108,643	$ (21,478)	$ 175,318
Common Stock, Shares, Outstanding, Beginning Balance at Apr. 30, 2010	14,205,462
Net income (loss)		(20,018)		(20,018)
Other comprehensive loss, net of tax			(460)	(460)
Stock-based compensation	3,995			3,995
Adjustments to excess tax benefit from stock-based compensation	(1,347)			(1,347)
Cash dividends		(5,130)		(5,130)
Exercise of stock-based compensation awards	394			394
Exercise of stock-based compensation awards, shares	27,401
Employee benefit plan contributions, shares	62,677
Employee benefit plan contributions	1,213			1,213
Balance at Apr. 30, 2011	92,408	83,495	(21,938)	153,965
Common Stock, Shares, Outstanding, Ending Balance at Apr. 30, 2011	14,295,540
Net income (loss)		(20,786)		(20,786)
Other comprehensive loss, net of tax			(5,669)	(5,669)
Stock-based compensation	3,413			3,413
Adjustments to excess tax benefit from stock-based compensation	(859)			(859)
Cash dividends		(1,287)		(1,287)
Exercise of stock-based compensation awards	12			12
Exercise of stock-based compensation awards, shares	19,410
Employee benefit plan contributions, shares	80,323
Employee benefit plan contributions	1,231			1,231
Balance at Apr. 30, 2012	96,205	61,422	(27,607)	130,020
Common Stock, Shares, Outstanding, Ending Balance at Apr. 30, 2012	14,395,273			14,395,273
Net income (loss)		9,758		9,758
Other comprehensive loss, net of tax			(4,543)	(4,543)
Stock-based compensation	3,509			3,509
Adjustments to excess tax benefit from stock-based compensation	(650)			(650)
Exercise of stock-based compensation awards	5,768			5,768
Exercise of stock-based compensation awards, shares	328,490
Employee benefit plan contributions, shares	98,817
Employee benefit plan contributions	2,333			2,333
Balance at Apr. 30, 2013	$ 107,165	$ 71,180	$ (32,150)	$ 146,195
Common Stock, Shares, Outstanding, Ending Balance at Apr. 30, 2013	14,822,580			14,822,580