Intangible Assets (Schedule Of Intangible Assets And Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2014	Apr. 30, 2014
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	$ 13,574	$ 13,574
Finite-lived intangible assets, Accumulated amortization	(8,344)	(7,960)
Finite-lived intangible assets, Net carrying amount	5,230	5,614
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	(4,572)	(4,403)
Finite-lived intangible assets, Net carrying amount	1,664	1,833
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	(2,112)	(2,034)
Finite-lived intangible assets, Net carrying amount	526	604
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	(1,560)	(1,423)
Finite-lived intangible assets, Net carrying amount	3,040	3,177
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	100	100
Finite-lived intangible assets, Accumulated amortization	$ (100)	$ (100)