Condensed Consolidated Statements Of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Statement of Other Comprehensive Income [Abstract]
Net loss	$ 2,057	$ (9,114)	$ 4,568	$ (14,806)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Change in pension benefits	142	(7,271)	423	(6,610)
Total Comprehensive Income (Loss)	$ 2,199	$ (16,385)	$ 4,991	$ (21,416)