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 - Shareholder's equity, Amount at Sep. 30, 2017			$ 492,246	$ 1,847,819	$ (739,157)	$ (89,919)	$ (12,474)	$ (335,491)
Increase (Decrease) in Stockholders' Equity
Issuance of shares			(2,733)		5,184
Equity-based compensation expense			3,500
Adjustment to market - SECT, SERP and other			(2,958)
Net earnings	$ 15,264			15,264
Dividends				(8,978)
Tax Cuts and Jobs Act, reclassification from AOCIL to retained earnings	(47,077)			47,077				(47,077)
Class A and B shares purchased					(5,118)
Issuance of shares - SECT						1,941
Purchase of shares - SECT	(7,914)					(7,914)
Adjustment to market						2,562	396
Other comprehensive income (loss)	40,254							40,254
End of period - Shareholder's equity, Amount at Mar. 31, 2018	1,255,704	$ 51,280	490,055	1,901,182	(739,091)	(93,330)	(12,078)	(342,314)
Beginning of period - Common Stock at Sep. 30, 2017									43,704,286			7,575,427
Increase (Decrease) in Stockholders' Equity
Conversion of Class B to Class A									31,272			(31,272)
End of period - Common Stock at Mar. 31, 2018									43,735,558			7,544,155
Beginning of period, Shares at Sep. 30, 2017										(10,933,003)			(3,333,927)	(654,753)
Increase (Decrease) in Stockholders' Equity
Class A and B shares issued related to equity compensation, shares										79,679			28,239
Class A and B shares purchased, shares										(37,784)			(22,165)
Issuance of shares - SECT														21,871
Purchase of shares - SECT														(91,081)
End of period, Shares at Mar. 31, 2018										(10,891,108)	(425,148)		(3,327,853)	(723,963)	(150,000)
Beginning of period - Shareholder's equity, Amount at Dec. 30, 2017			498,699	1,849,118	(739,210)	(98,990)	(13,311)	(319,637)
Increase (Decrease) in Stockholders' Equity
Issuance of shares			(1,100)		2,503
Equity-based compensation expense			1,499
Adjustment to market - SECT, SERP and other			(9,043)
Net earnings	13,965			13,965
Dividends				(8,978)
Tax Cuts and Jobs Act, reclassification from AOCIL to retained earnings	(47,077)			47,077				(47,077)
Class A and B shares purchased					(2,384)
Issuance of shares - SECT						1,941
Purchase of shares - SECT						(4,091)
Adjustment to market						7,810	1,233
Other comprehensive income (loss)	24,400							24,400
End of period - Shareholder's equity, Amount at Mar. 31, 2018	1,255,704	51,280	490,055	1,901,182	(739,091)	(93,330)	(12,078)	(342,314)
Beginning of period - Common Stock at Dec. 30, 2017									43,715,586			7,564,127
Increase (Decrease) in Stockholders' Equity
Conversion of Class B to Class A									19,972			(19,972)
End of period - Common Stock at Mar. 31, 2018									43,735,558			7,544,155
Beginning of period, Shares at Dec. 30, 2017										(10,901,537)			(3,328,064)	(699,415)
Increase (Decrease) in Stockholders' Equity
Class A and B shares issued related to equity compensation, shares										15,193			22,361
Class A and B shares purchased, shares										(4,764)			(22,150)
Issuance of shares - SECT														21,871
Purchase of shares - SECT														(46,419)
End of period, Shares at Mar. 31, 2018										(10,891,108)	(425,148)		(3,327,853)	(723,963)	(150,000)
Increase (Decrease) in Stockholders' Equity
Adoption of revenue recognition standard | ASC 606				0
Beginning of period - Shareholder's equity, Amount at Sep. 29, 2018	1,224,986		502,257	1,973,514	(738,494)	(118,449)	(72,941)	(372,181)
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	86,428			86,428
Dividends				(17,430)
Tax Cuts and Jobs Act, reclassification from AOCIL to retained earnings	0			0				0
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)	1,800							1,800
End of period - Shareholder's equity, Amount at Mar. 30, 2019	1,314,442	51,280	510,538	2,057,435	(749,845)	(109,506)	(75,079)	(370,381)
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)			3,323,996	(983,772)
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)
Increase (Decrease) in Stockholders' Equity
Adoption of revenue recognition standard | ASC 606				14,923
Beginning of period - Shareholder's equity, Amount at Dec. 29, 2018			491,945	2,023,803	(747,900)	(102,182)	(67,597)	(376,085)
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	42,359			42,359
Dividends				(8,727)
Tax Cuts and Jobs Act, reclassification from AOCIL to retained earnings	0			0				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)	5,704							5,704
End of period - Shareholder's equity, Amount at Mar. 30, 2019	$ 1,314,442	$ 51,280	$ 510,538	2,057,435	$ (749,845)	$ (109,506)	$ (75,079)	$ (370,381)
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)			(3,348,499)	(899,864)
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)
Increase (Decrease) in Stockholders' Equity
Adoption of revenue recognition standard | ASC 606				$ 0