Prior Year Reclassification (Summary Of Effect Of Reclassifications) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating, general and administrative expenses	$ 226,719	$ 211,732
Income from operations	37,428	17,820
Other income (expense)	2,676	(1,841)
Unrealized (gain) loss in SERP	2,676	(1,008)
Net cash provided by operating activities	124,763	32,651
Payments for SERP investment	(91)	(1,708)
Net cash used in investing activities	$ (25,016)	(30,333)
As Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating, general and administrative expenses		213,573
Income from operations		15,979
Net cash provided by operating activities		33,659
Payments for SERP investment		(2,716)
Net cash used in investing activities		(31,341)
Reclassifications [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating, general and administrative expenses		(1,841)
Income from operations		1,841
Other income (expense)		(1,841)
Unrealized (gain) loss in SERP		(1,008)
Net cash provided by operating activities		(1,008)
Payments for SERP investment		1,008
Net cash used in investing activities		$ 1,008