Prior Year Reclassification (Summary Of Effect Of Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating, general and administrative expenses	$ 236,886	$ 210,373	$ 463,605	$ 422,105
Income from operations	56,002	26,297	93,430	44,118
Other income (expense)	$ (2,618)	(428)	58	(2,270)
Unrealized (gain) loss in SERP			383	(1,360)
Net cash provided by operating activities			139,075	77,606
Change in SERP investment			(677)	(2,116)
Net cash used in investing activities			$ (80,609)	(47,091)
As Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating, general and administrative expenses		210,801		424,375
Income from operations		25,869		41,848
Net cash provided by operating activities				78,966
Change in SERP investment				(3,476)
Net cash used in investing activities				(48,451)
Reclassifications [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating, general and administrative expenses		(428)		(2,270)
Income from operations		428		2,270
Other income (expense)		$ (428)		(2,270)
Unrealized (gain) loss in SERP				(1,360)
Net cash provided by operating activities				(1,360)
Change in SERP investment				1,360
Net cash used in investing activities				$ 1,360