Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Apr. 30, 2017
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 5,965		$ 5,362
Unrecognized tax benefits that would impact effective tax rate	3,914
Accrued interest and penalties related to unrecognized tax benefits	160		$ 141
Net interest and penalties included in income tax expense	19	$ 28
Expected decrease in unrecognized tax benefits	$ 1,242