Quarterly Financial Data (Unaudited) (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 28, 2017 USD ($) $ / shares	Jan. 27, 2017 USD ($) $ / shares	Oct. 28, 2016 USD ($) $ / shares	Jul. 29, 2016 USD ($) $ / shares	Apr. 29, 2016 USD ($) $ / shares	Jan. 22, 2016 USD ($) $ / shares	Oct. 23, 2015 USD ($) $ / shares	Jul. 24, 2015 USD ($) $ / shares	Apr. 28, 2017 USD ($) $ / shares	Apr. 29, 2016 USD ($) $ / shares	Apr. 24, 2015 USD ($) $ / shares	Jun. 09, 2017 stockholder
Subsequent Event [Line Items]
Net Sales from Continuing Operations | $	$ 99,923	$ 112,820	$ 96,158	$ 85,941	$ 102,394	$ 107,897	$ 94,281	$ 83,044	$ 394,842	$ 387,616	$ 379,313
Operating Income (Loss) from Continuing Operations | $	9,508	17,121	(4,768)	8,265	10,334	11,424	5,330	5,986	30,126	33,074	(5,357)
Net Income (Loss) from Continuing Operations | $	6,757	9,838	(4,857)	5,298	5,932	6,416	1,278	2,582	$ 126,467	$ 24,222	$ 16,553
Income from Discontinued Operations, Net of Income Taxes | $	$ 102,110	$ (1,617)	$ 5,074	$ 3,864	$ (5,351)	$ 6,515	$ 5,152	$ 1,698
Earnings Per Share - Net Income
Basic (in dollars per share)	$ 5.47	$ 0.41	$ 0.01	$ 0.46	$ 0.03	$ 0.62	$ 0.29	$ 0.19	$ 6.37	$ 1.14	$ 0.70
Diluted (in dollars per share)	5.39	0.41	0.01	0.46	0.03	0.62	0.29	0.19	6.28	1.13	0.70
Common stock sale prices - High (in dollars per share)	67.25	57.94	41.09	46.83	48.14	44.34	49.92	51.88
Common stock sale prices - Low (in dollars per share)	55.49	40.05	35.90	35.67	38.92	37.51	42.51	43.02
Cash dividends paid (in dollars per share)	$ 0.34	$ 0.34	$ 0.34	$ 0.34	$ 0.34	$ 0.34	$ 0.31	$ 0.31	$ 1.36	$ 1.30	$ 1.24
Subsequent Event
Earnings Per Share - Net Income
Number of registered stockholders of common stock | stockholder												14,648