Note 8 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 27, 2018	Jan. 28, 2017	Jan. 27, 2018	Jan. 28, 2017	Apr. 28, 2018
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	$ (4.3)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ (7.0)
Effective Income Tax Rate Reconciliation, Percent	10.90%	34.20%	26.90%	34.20%
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent					30.40%