QUARTERLY FINANCIAL SUMMARY (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 01, 2021	Jul. 02, 2021	Apr. 02, 2021	Jan. 01, 2021	Oct. 02, 2020	Jun. 26, 2020	Mar. 27, 2020	Dec. 27, 2019	Oct. 01, 2021	Oct. 02, 2020	Sep. 27, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net sales	$ 166,260	$ 213,568	$ 206,156	$ 165,667	$ 164,681	$ 138,390	$ 163,084	$ 128,054	$ 751,651	$ 594,209	$ 562,419
Gross profit	68,330	97,511	93,254	75,030	73,687	62,562	75,132	53,612	334,125	264,993	249,756
Operating profit	13,591	38,099	36,036	23,557	19,546	12,929	31,794	6,801	111,283	71,070	63,774
Income before income taxes	10,527	39,074	37,310	26,011	21,179	15,557	28,377	8,589	112,922	73,702	66,507
Income tax expense	3,601	10,300	9,476	6,164	5,632	2,688	7,990	2,159	29,541	18,469	15,094
Net income	$ 6,926	$ 28,774	$ 27,834	$ 19,847	$ 15,547	$ 12,869	$ 20,387	$ 6,430	$ 83,381	$ 55,233	$ 51,413
Class A
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income per common share - Basic (USD per share)	$ 0.70	$ 2.87	$ 2.78	$ 1.99	$ 1.56	$ 1.29	$ 2.05	$ 0.65	$ 8.34	$ 5.54	$ 5.18
Net income per common share - Diluted (USD per share)	0.68	2.83	2.74	1.96	1.53	1.27	2.02	0.64	8.21	5.47	5.11
Class B
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income per common share - Basic (USD per share)	0.62	2.61	2.53	1.81	1.42	1.17	1.86	0.59	7.57	5.04	4.71
Net income per common share - Diluted (USD per share)	$ 0.68	$ 2.83	$ 2.74	$ 1.96	$ 1.53	$ 1.27	$ 2.02	$ 0.64	$ 8.21	$ 5.47	$ 5.11