Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jul. 31, 2016	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Income Tax Disclosure [Abstract]
Operating loss carryforwards		$ 61,154
Alternative minimum tax credit carryforwards		7
Valuation allowance		60	$ 84
Valuation allowance, increase (decrease)		(24)	(144)
Unrecognized tax benefits		5,362	6,484	$ 8,043
Unrecognized tax benefits that would impact effective tax rate		3,522
Increase (decrease) in unrecognized tax benefits		(1,122)
Accrued interest and penalties		141	217
Increase in tax expense		(76)	$ 65
Decrease in unrecognized tax benefits is reasonable possible		$ 1,242
Income tax benefit from share-based compensation	$ 3,046