Accrued Restructuring Charges (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended
	Jan. 31, 2015	Jan. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	$ 0	$ 171,000
Lease Abandonment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred		150,000
Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred		$ 21,000