Inventories (Components Of Inventories) (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Apr. 30, 2013
Inventories [Abstract]
Raw materials	$ 12,797	$ 11,823
Work-in-process	16,770	17,170
Finished goods	11,087	11,318
Total FIFO inventories	40,654	40,311
Reserve to adjust inventories to LIFO value	(10,983)	(10,973)
Total LIFO inventories	$ 29,671	$ 29,338