Note 11 - Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Apr. 27, 2019	Apr. 28, 2018	Apr. 29, 2017
Operating Leases, Rent Expense, Total	$ 18.2	$ 13.3	$ 12.0
Raw Material [Member]
Purchase Obligation, Due in Next Twelve Months	12.7
Commitments for Plant and Equipment [Member]
Purchase Obligation, Due in Next Twelve Months	$ 7.1