Restructuring Charges - Accrued Liability Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Restructuring Cost and Reserve [Line Items]
Balance at April 30, 2016			$ 1,043
Restructuring charges	$ 767	$ 0	1,094	$ 0
Utilization			(1,766)
Balance at October 31, 2016	371		371
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Balance at April 30, 2016			497
Restructuring charges			459
Utilization			(929)
Balance at October 31, 2016	27		27
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Balance at April 30, 2016			546
Restructuring charges			635
Utilization			(837)
Balance at October 31, 2016	$ 344		$ 344