Consolidated Condensed Statements of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock At Cost	Stock Employee Compensation Trust (SECT)	Supplemental Retirement Plan (SERP) Trust	Accumulated Other Comprehensive Loss	Class A Common Stock	Class A Common Stock Treasury Stock At Cost	Class A Common Stock Stock Employee Compensation Trust (SECT)	Class B Common Stock	Class B Common Stock Treasury Stock At Cost	Class B Common Stock Stock Employee Compensation Trust (SECT)	Class B Common Stock Supplemental Retirement Plan (SERP) Trust
Beginning of period at Sep. 29, 2018		$ 51,280	$ 502,257	$ 1,974,125	$ (738,494)	$ (118,449)	$ (72,941)	$ (372,792)
Increase (Decrease) in Stockholders' Equity
Issuance of shares			1,070		4,968
Equity-based compensation expense			3,691
Adjustment to market - SECT, SERP and other			3,520
Net earnings	$ 83,828			83,828
Dividends				(17,430)
Adoption of ASC 606 | ASC 606				14,923
Class A and B shares purchased					(16,319)
Issuance of shares - SECT						17,679
Purchase of shares - SECT	(7,354)					(7,354)
Adjustment to market						(1,382)	(2,138)
Other comprehensive income (loss)	4,400							4,400
End of period at Mar. 30, 2019	1,314,442	51,280	510,538	2,055,446	(749,845)	(109,506)	(75,079)	(368,392)
Beginning of period - Common Stock at Sep. 29, 2018									43,784,489			7,495,224
Increase (Decrease) in Stockholders' Equity
Conversion of Class B to Class A									946			(946)
End of period - Common Stock at Mar. 30, 2019									43,785,435			7,494,278
Beginning of period, Shares at Sep. 29, 2018										(10,872,575)	(425,148)		(3,323,996)	(983,772)	(876,170)
Increase (Decrease) in Stockholders' Equity
Class A and B shares issued related to equity compensation, shares										71,863			98,329
Class A and B shares purchased, shares										(82,068)			(121,583)
Issuance of shares - SECT														221,326
Purchase of shares - SECT														(84,081)
End of period, Shares at Mar. 30, 2019										(10,882,780)	(425,148)		(3,347,250)	(846,527)	(876,170)
Beginning of period at Dec. 29, 2018		51,280	491,945	2,023,114	(747,900)	(102,182)	(67,597)	(375,396)
Increase (Decrease) in Stockholders' Equity
Issuance of shares			(1,390)		3,833
Equity-based compensation expense			1,683
Adjustment to market - SECT, SERP and other			18,300
Net earnings	41,059			41,059
Dividends				(8,727)
Adoption of ASC 606 | ASC 606				0
Class A and B shares purchased					(5,778)
Issuance of shares - SECT						8,918
Purchase of shares - SECT						(5,424)
Adjustment to market						(10,818)	(7,482)
Other comprehensive income (loss)	7,004							7,004
End of period at Mar. 30, 2019	1,314,442	51,280	510,538	2,055,446	(749,845)	(109,506)	(75,079)	(368,392)
Beginning of period - Common Stock at Dec. 29, 2018									43,785,435			7,494,278
Increase (Decrease) in Stockholders' Equity
Conversion of Class B to Class A									0			0
End of period - Common Stock at Mar. 30, 2019									43,785,435			7,494,278
Beginning of period, Shares at Dec. 29, 2018										(10,897,407)	(425,148)		(3,348,499)	(899,864)	(876,170)
Increase (Decrease) in Stockholders' Equity
Class A and B shares issued related to equity compensation, shares										48,122			39,536
Class A and B shares purchased, shares										(33,495)			(38,287)
Issuance of shares - SECT														113,749
Purchase of shares - SECT														(60,412)
End of period, Shares at Mar. 30, 2019										(10,882,780)	(425,148)		(3,347,250)	(846,527)	(876,170)
Beginning of period at Sep. 28, 2019	1,322,481	51,280	510,546	2,128,739	(769,569)	(111,492)	(71,546)	(415,477)
Increase (Decrease) in Stockholders' Equity
Issuance of shares			3,767		4,448
Equity-based compensation expense			3,271
Adjustment to market - SECT, SERP and other			(67,864)
Net earnings	99,772			99,772
Dividends				(17,049)
Adoption of ASC 606 | ASC 606				0
Class A and B shares purchased					(191,961)
Issuance of shares - SECT						18,325
Purchase of shares - SECT	(6,209)					(6,209)
Adjustment to market						38,990	28,874
Other comprehensive income (loss)	8,833							8,833
End of period at Mar. 28, 2020	1,245,678	51,280	449,720	2,211,462	(957,082)	(60,386)	(42,672)	(406,644)
Beginning of period - Common Stock at Sep. 28, 2019									43,794,935			7,484,778
Increase (Decrease) in Stockholders' Equity
Conversion of Class B to Class A									4,294			(4,294)
End of period - Common Stock at Mar. 28, 2020									43,799,229			7,480,484
Beginning of period, Shares at Sep. 28, 2019										(11,101,512)	(425,148)		(3,345,489)	(886,300)	(826,170)
Increase (Decrease) in Stockholders' Equity
Class A and B shares issued related to equity compensation, shares										17,599			138,784
Class A and B shares purchased, shares										(2,286,697)			(138,172)
Issuance of shares - SECT														221,256
Purchase of shares - SECT														(69,562)
End of period, Shares at Mar. 28, 2020										(13,370,610)	(425,148)		(3,344,877)	(734,606)	(826,170)
Beginning of period at Dec. 28, 2019		51,280	518,822	2,170,105	(828,453)	(115,503)	(71,381)	(388,179)
Increase (Decrease) in Stockholders' Equity
Issuance of shares			(722)		3,921
Equity-based compensation expense			890
Adjustment to market - SECT, SERP and other			(69,270)
Net earnings	49,745			49,745
Dividends				(8,388)
Adoption of ASC 606 | ASC 606				0
Class A and B shares purchased					(132,550)
Issuance of shares - SECT						18,325
Purchase of shares - SECT						(3,769)
Adjustment to market						40,561	28,709
Other comprehensive income (loss)	(18,465)							(18,465)
End of period at Mar. 28, 2020	$ 1,245,678	$ 51,280	$ 449,720	$ 2,211,462	$ (957,082)	$ (60,386)	$ (42,672)	$ (406,644)
Beginning of period - Common Stock at Dec. 28, 2019									43,796,335			7,483,378
Increase (Decrease) in Stockholders' Equity
Conversion of Class B to Class A									2,894			(2,894)
End of period - Common Stock at Mar. 28, 2020									43,799,229			7,480,484
Beginning of period, Shares at Dec. 28, 2019										(11,767,540)	(425,148)		(3,260,602)	(914,896)	(826,170)
Increase (Decrease) in Stockholders' Equity
Class A and B shares issued related to equity compensation, shares										14,521			44,217
Class A and B shares purchased, shares										(1,617,591)			(128,492)
Issuance of shares - SECT														221,256
Purchase of shares - SECT														(40,966)
End of period, Shares at Mar. 28, 2020										(13,370,610)	(425,148)		(3,344,877)	(734,606)	(826,170)