Restructuring Charges - Accrued Liability Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Restructuring Cost and Reserve [Line Items]
Beginning balance				$ 1,043				$ 0	$ 1,043	$ 0
Restructuring charges	$ 1,108	$ 0	$ 767	327	$ 1,575	$ 0	$ 0	0	2,202	1,575	$ 0
Payments									(1,250)	(532)
Non-cash settlements of restructuring charges									(588)
Ending balance	1,407				1,043				1,407	1,043	0
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance				497				0	497	0
Restructuring charges									1,567	1,029
Payments									(956)	(532)
Non-cash settlements of restructuring charges									0
Ending balance	1,108				497				1,108	497	0
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance				$ 546				$ 0	546	0
Restructuring charges									635	546
Payments									(294)	0
Non-cash settlements of restructuring charges									(588)
Ending balance	$ 299				$ 546				$ 299	$ 546	$ 0