Condensed Consolidated Statements Of Changes In Stockholders' Equity - USD ($)	Class A Common Stock [Member] Common Stock [Member]	Class B Common Stock [Member] Common Stock [Member]	Paid-in Capital in Excess of Par Value [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Total
Balance at Sep. 30, 2017	$ 704,202	$ 308,787	$ 12,311,249		$ 497,727,765	$ 511,052,003
Balance (in shares) at Sep. 30, 2017	14,084,044	6,175,732
Net income					45,146,740	45,146,740
Cash dividends					(3,250,228)	(3,250,228)
Common stock conversions	$ 1,710	$ (1,710)
Common stock conversions (in shares)	34,200	(34,200)
Balance at Dec. 30, 2017	$ 705,912	$ 307,077	12,311,249		539,624,277	552,948,515
Balance (in shares) at Dec. 30, 2017	14,118,244	6,141,532
Balance at Sep. 30, 2017	$ 704,202	$ 308,787	12,311,249		497,727,765	511,052,003
Balance (in shares) at Sep. 30, 2017	14,084,044	6,175,732
Net income						54,441,527
Balance at Mar. 31, 2018	$ 706,302	$ 306,687	12,311,249		545,668,323	558,992,561
Balance (in shares) at Mar. 31, 2018	14,126,044	6,133,732
Balance at Dec. 30, 2017	$ 705,912	$ 307,077	12,311,249		539,624,277	552,948,515
Balance (in shares) at Dec. 30, 2017	14,118,244	6,141,532
Net income					9,294,788	9,294,788
Cash dividends					(3,250,742)	(3,250,742)
Common stock conversions	$ 390	$ (390)
Common stock conversions (in shares)	7,800	(7,800)
Balance at Mar. 31, 2018	$ 706,302	$ 306,687	12,311,249		545,668,323	558,992,561
Balance (in shares) at Mar. 31, 2018	14,126,044	6,133,732
Balance at Sep. 29, 2018	$ 707,269	$ 305,720	12,311,249		582,089,570	595,413,808
Balance (in shares) at Sep. 29, 2018	14,145,385	6,114,391
Net income					22,152,337	22,152,337
Other comprehensive (expense) income, net of income tax				$ 340,339		340,339
Cash dividends					(3,251,148)	(3,251,148)
Balance at Dec. 29, 2018	$ 707,269	$ 305,720	12,311,249	340,339	600,990,759	614,655,336
Balance (in shares) at Dec. 29, 2018	14,145,385	6,114,391
Balance at Sep. 29, 2018	$ 707,269	$ 305,720	12,311,249		582,089,570	595,413,808
Balance (in shares) at Sep. 29, 2018	14,145,385	6,114,391
Net income						37,152,377
Other comprehensive (expense) income, net of income tax						(119,109)
Balance at Mar. 30, 2019	$ 708,867	$ 304,122	12,311,249	(119,109)	612,739,647	625,944,776
Balance (in shares) at Mar. 30, 2019	14,177,335	6,082,441
Balance at Dec. 29, 2018	$ 707,269	$ 305,720	12,311,249	340,339	600,990,759	614,655,336
Balance (in shares) at Dec. 29, 2018	14,145,385	6,114,391
Net income					15,000,040	15,000,040
Other comprehensive (expense) income, net of income tax				(459,448)		(459,448)
Cash dividends					(3,251,152)	(3,251,152)
Common stock conversions	$ 1,598	$ (1,598)
Common stock conversions (in shares)	31,950	(31,950)
Balance at Mar. 30, 2019	$ 708,867	$ 304,122	$ 12,311,249	$ (119,109)	$ 612,739,647	$ 625,944,776
Balance (in shares) at Mar. 30, 2019	14,177,335	6,082,441