Intangible and Other Assets, Net (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Apr. 30, 2012
Finite-Lived Intangible Assets, Gross	$ 24,773	$ 23,270
Deferred order entry costs	1,275	1,320
Prepaid expenses	3,308	3,315
Finite-Lived Intangible Assets, Accumulated Amortization	10,212	9,290
Software and Software Development Costs [Member]
Finite-Lived Intangible Assets, Gross	1,704	1,964
Finite-Lived Intangible Assets, Accumulated Amortization	1,693	1,905
Deferred Order Entry Costs [Member]
Finite-Lived Intangible Assets, Gross	1,275	1,320
Finite-Lived Intangible Assets, Accumulated Amortization	0	0
Prepaid Expenses [Member]
Finite-Lived Intangible Assets, Gross	3,308	3,315
Finite-Lived Intangible Assets, Accumulated Amortization	0	0
Customer Contracts and Relationships [Member]
Finite-Lived Intangible Assets, Gross	16,749	15,000
Finite-Lived Intangible Assets, Accumulated Amortization	7,561	6,612
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Gross	1,737	1,671
Finite-Lived Intangible Assets, Accumulated Amortization	$ 958	$ 773