Note 10 - Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Apr. 29, 2017	Apr. 30, 2016	May 02, 2015
Operating Leases, Rent Expense	$ 12.0	$ 9.2	$ 8.2
Leveraged Leases, Net Investment in Leveraged Leases Disclosure, Residual Value of Leased Assets	2.5
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	$ 2.6