Restructuring Charges - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 16	$ 767	$ 56	$ 1,094
2016 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 767		$ 1,094
Restructuring charges, incurred to date	2,700		2,700
2017 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	16		56
Restructuring charges, incurred to date	$ 1,200		$ 1,200