Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Apr. 30, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 7,667		$ 6,484
Unrecognized tax benefits that would impact effective tax rate	5,020
Accrued interest and penalties related to unrecognized tax benefits	289		$ 217
Net interest and penalties included in income tax expense	72	$ 154
Expected decrease in unrecognized tax benefits	$ 3,130