Consolidated Statements Of Shareholders' Equity And Comprehensive Loss (USD $) In Thousands, except Share data	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning Balance at Apr. 30, 2009	$ 82,293	$ 136,074	$ (14,685)	$ 203,682
Common Stock, Shares, Outstanding, Beginning Balance at Apr. 30, 2009	14,094,449
Net loss		(22,341)		(22,341)
Change in pension benefits			(6,793)	(6,793)
Total Comprehensive Loss				(29,134)
Stock-based compensation	4,392			4,392
Adjustments to excess tax benefit from stock-based compensation	(439)			(439)
Cash dividends		(5,090)		(5,090)
Exercise of stock-based compensation awards	719			719
Exercise of stock-based compensation awards, shares	54,070
Employee benefit plan contributions, shares	56,943
Employee benefit plan contributions	1,188			1,188
Balance at Apr. 30, 2010	88,153	108,643	(21,478)	175,318
Common Stock, Shares, Outstanding, Ending Balance at Apr. 30, 2010	14,205,462
Net loss		(20,018)		(20,018)
Change in pension benefits			(460)	(460)
Total Comprehensive Loss				(20,478)
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			14,295,540
Net loss		(20,786)		(20,786)
Change in pension benefits			(5,669)	(5,669)
Total Comprehensive Loss				(26,455)
Stock-based compensation	3,413			3,413
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