Note 6 - Recently Issued Accounting Pronouncements (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 28, 2017	Oct. 29, 2016	Oct. 28, 2017	Oct. 29, 2016
Income Tax Expense (Benefit)	$ 16,932,000	$ 12,788,000	$ 36,701,000	$ 27,858,000
Reclassification of Excess Tax Benefits from Financing to Operating Activities [Member] | Six Months Ended October 29, 2016 [Member]
Prior Period Reclassification Adjustment				$ 76,000
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit)	$ 480,000		561,000
Reclassification of Deferred Taxes from Current to Non-current [Member] | April 29, 2017 [Member]
Prior Period Reclassification Adjustment			$ 3,900,000