Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Apr. 30, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 8,089		$ 6,484
Unrecognized tax benefits that would impact effective tax rate	5,295
Accrued interest and penalties related to unrecognized tax benefits	321		$ 217
Net interest and penalties included in income tax expense	104	$ 186
Expected decrease in unrecognized tax benefits	$ 3,153