Quarterly Financial Data (Unaudited) (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 29, 2016 USD ($) $ / shares	Jan. 22, 2016 USD ($) $ / shares	Oct. 23, 2015 USD ($) $ / shares	Jul. 24, 2015 USD ($) $ / shares	Apr. 24, 2015 USD ($) $ / shares	Jan. 23, 2015 USD ($) $ / shares	Oct. 24, 2014 USD ($) $ / shares	Jul. 25, 2014 USD ($) $ / shares	Apr. 29, 2016 USD ($) $ / shares	Apr. 24, 2015 USD ($) $ / shares	Apr. 25, 2014 USD ($) $ / shares	Jun. 01, 2016 stockholder
Subsequent Event [Line Items]
Net Sales | $	$ 345,587	$ 346,505	$ 325,021	$ 321,713	$ 332,393	$ 357,177	$ 333,279	$ 326,341	$ 1,338,827	$ 1,349,190	$ 1,328,552
Operating income | $	(1,535)	18,060	11,434	8,262	937	7,673	9,012	64	36,221	17,686	33,125
Net income (loss) | $	$ 580	$ 12,931	$ 6,431	$ 4,280	$ 5,610	$ 5,920	$ 6,039	$ (1,016)	$ 24,222	$ 16,553	$ 33,685
Earnings Per Share - Net Income
Basic (in dollars per share)	$ 0.03	$ 0.62	$ 0.29	$ 0.19	$ 0.24	$ 0.25	$ 0.26	$ (0.04)	$ 1.14	$ 0.70	$ 1.27
Diluted (in dollars per share)	0.03	0.62	0.29	0.19	0.24	0.25	0.25	(0.04)	1.13	0.70	1.26
Common stock sale prices - High (in dollars per share)	48.14	44.34	49.92	51.88	59.64	56.34	49.10	51.11
Common stock sale prices - Low (in dollars per share)	38.92	37.51	42.51	43.02	43.72	47.91	42.70	44.67
Cash dividends paid (in dollars per share)	$ 0.34	$ 0.34	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 1.3	$ 1.24	$ 1.205
Subsequent Event
Earnings Per Share - Net Income
Number of registered stockholders of common stock | stockholder												15,665