Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Preferred Stock [Member] Series C Preferred Stock [Member]	Preferred Stock [Member] Series D Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member] Series C Preferred Stock [Member]	Treasury Stock [Member] Common Treasury Stock [Member]	Total
Beginning and end of year (in shares) at Apr. 29, 2017	150,000		50,616,000				150,000	4,033,000
Beginning and end of year at Apr. 29, 2017	$ 150		$ 506	$ 35,638	$ 227,928	$ (604)	$ (5,100)	$ (12,900)	$ 245,618
Beginning of year at Apr. 30, 2016			$ 506	34,570	190,733	(1,807)
Series D preferred redeemed
Beginning of year (in shares) at Apr. 30, 2016			50,589,000
Stock options exercised (in shares)			27,000
Stock options exercised				365
Stock-based compensation				208
Stock-based tax benefits				495
Net income					107,045				107,045
Common stock cash dividend					(69,850)
Cash flow hedges						1,110			1,110
Other						93			93
Beginning and end of year (in shares) at Apr. 28, 2018	150,000		50,651,000				150,000	4,033,000
Beginning and end of year at Apr. 28, 2018	$ 150		$ 507	36,358	307,824	4,601	$ (5,100)	$ (12,900)	331,440
Beginning of year at Apr. 29, 2017	$ 150		$ 506	35,638	227,928	(604)	$ (5,100)	$ (12,900)	245,618
Series D preferred redeemed
Beginning of year (in shares) at Apr. 29, 2017	150,000		50,616,000				150,000	4,033,000
Stock options exercised (in shares)			35,000
Stock options exercised			$ 1	559
Stock-based compensation				161
Stock-based tax benefits
Net income					149,774				149,774
Common stock cash dividend					(69,878)
Cash flow hedges						5,227			5,227
Other						(22)			(22)
Beginning and end of year (in shares) at Apr. 27, 2019	150,000		50,678,000				150,000	4,033,000
Beginning and end of year at Apr. 27, 2019	$ 150		$ 507	37,065	313,430	(1,543)	$ (5,100)	$ (12,900)	331,609
Beginning of year at Apr. 28, 2018	$ 150		$ 507	36,358	307,824	4,601	$ (5,100)	$ (12,900)	$ 331,440
Series D preferred redeemed
Beginning of year (in shares) at Apr. 28, 2018	150,000		50,651,000				150,000	4,033,000
Stock options exercised (in shares)			27,000						27,300
Stock options exercised				456
Stock-based compensation				251
Stock-based tax benefits
Net income					140,853				$ 140,853
Common stock cash dividend					$ (135,247)
Cash flow hedges						(6,318)			(6,318)
Other						$ 174			$ 174