Intangible Assets (Schedule Of Intangible Assets And Goodwill) (Details) - USD ($) $ in Thousands	Jul. 31, 2015	Apr. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	$ 13,574	$ 13,574
Finite-lived intangible assets, Accumulated amortization	(9,807)	(9,472)
Finite-lived intangible assets, Net carrying amount	3,767	4,102
Customer-Related [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	6,236	6,236
Finite-lived intangible assets, Accumulated amortization	(5,218)	(5,083)
Finite-lived intangible assets, Net carrying amount	1,018	1,153
Technology-Based [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	2,638	2,638
Finite-lived intangible assets, Accumulated amortization	(2,418)	(2,346)
Finite-lived intangible assets, Net carrying amount	220	292
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	4,600	4,600
Finite-lived intangible assets, Accumulated amortization	(2,071)	(1,943)
Finite-lived intangible assets, Net carrying amount	2,529	2,657
Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	100	100
Finite-lived intangible assets, Accumulated amortization	$ (100)	$ (100)