Stock-Based Compensation (Stock-Based Compensation Expense Allocated) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 3,295	$ 3,509	$ 3,413
Cost Of Sales And Distribution [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	505	606	531
Selling And Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	801	859	715
General And Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,989	$ 2,044	$ 2,167