Restructuring Charges - Accrued Liability Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Restructuring Cost and Reserve [Line Items]
Balance at April 30, 2016	$ 1,043
Restructuring charges	327	$ 0
Payments	(470)
Balance at July 31, 2016	900
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Balance at April 30, 2016	497
Restructuring charges	327
Payments	(341)
Balance at July 31, 2016	483
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Balance at April 30, 2016	546
Restructuring charges	0
Payments	(129)
Balance at July 31, 2016	$ 417