Quarterly Results of Operations (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 24, 2017	Sep. 24, 2017	Jun. 25, 2017	Mar. 31, 2019	Apr. 01, 2018	Mar. 26, 2017
Summarized quarterly financial data
Fiscal period duration	91 days	91 days	91 days	91 days	98 days	91 days	91 days	91 days	364 days	371 days	364 days
Revenues	$ 144,963,800	$ 152,294,500	$ 158,636,100	$ 150,919,400	$ 148,920,100	$ 146,260,300	$ 145,083,500	$ 140,010,800	$ 606,813,800	$ 580,274,700	$ 533,295,100
Cost of goods sold	116,696,600	121,295,800	127,241,400	120,221,300	117,381,400	116,660,500	115,160,400	110,844,000	485,455,100	460,046,300	421,527,300
Gross profit	28,267,200	30,998,700	31,394,700	30,698,100	31,538,700	29,599,800	29,923,100	29,166,800	121,358,700	120,228,400	111,767,800
Selling, general and administrative expenses	27,280,300	27,494,800	29,477,300	28,961,300	30,357,600	27,413,200	26,674,400	27,881,500	113,213,700	112,326,700	108,416,300
Income from operations	986,900	3,503,900	1,917,400	1,736,800	1,181,100	2,186,600	3,248,700	1,285,300	8,145,000	7,901,700	2,544,900
Interest, net	186,700	247,900	244,800	174,400	89,500	114,500	156,500	68,600	853,800	429,100	58,600
Income before provision for income taxes	800,200	3,256,000	1,672,600	1,562,400	1,091,600	2,072,100	3,092,200	1,216,700	7,291,200	7,472,600	2,486,300
Provision for income taxes	308,200	551,400	481,800	404,000	(76,800)	501,900	1,318,300	533,800	1,745,400	2,277,200	1,041,200
Net income	$ 492,000	$ 2,704,600	$ 1,190,800	$ 1,158,400	$ 1,168,400	$ 1,570,200	$ 1,773,900	$ 682,900	$ 5,545,800	$ 5,195,400	$ 1,445,100
Diluted earnings per share (in dollars per share)	$ 0.06	$ 0.32	$ 0.14	$ 0.13	$ 0.14	$ 0.19	$ 0.21	$ 0.08	$ 0.65	$ 0.61	$ 0.17
Cash dividends declared per common share (in dollars per share)	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.80	$ 0.80	$ 0.80