Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balance, at Dec. 29, 2018	$ 9,949	$ 1,163,545	$ 262	$ (150,857)	$ 1,022,899
Balance, shares at Dec. 29, 2018	33,047,807			6,149,364
Net income		49,098			49,098
Other comprehensive income, net of reclassification adjustments and tax			1,203		1,203
Dividends paid		(25,016)			(25,016)
Balance, at Sep. 28, 2019	$ 9,949	1,187,627	1,465	$ (150,857)	1,048,184
Balance, shares at Sep. 28, 2019	33,047,807			6,149,364
Balance, at Jun. 29, 2019	$ 9,949	1,181,647	1,337	$ (150,857)	1,042,076
Balance, shares at Jun. 29, 2019	33,047,807			6,149,364
Net income		14,319			14,319
Other comprehensive income, net of reclassification adjustments and tax			127		127
Dividends paid		(8,339)			(8,339)
Balance, at Sep. 28, 2019	$ 9,949	1,187,627	1,465	$ (150,857)	1,048,184
Balance, shares at Sep. 28, 2019	33,047,807			6,149,364
Balance, at Dec. 28, 2019	$ 9,949	1,198,173	1,480	$ (150,857)	1,058,745
Balance, shares at Dec. 28, 2019	33,047,807			6,149,364
Net income		99,497			99,497
Other comprehensive income, net of reclassification adjustments and tax			1,479		1,479
Dividends paid		(25,016)			(25,016)
Balance, at Sep. 26, 2020	$ 9,949	1,272,655	2,959	$ (150,857)	1,134,706
Balance, shares at Sep. 26, 2020	33,047,807			6,149,364
Balance, at Jun. 27, 2020	$ 9,949	1,249,657	2,598	$ (150,857)	1,111,347
Balance, shares at Jun. 27, 2020	33,047,807			6,149,364
Net income		31,336			31,336
Other comprehensive income, net of reclassification adjustments and tax			362		362
Dividends paid		(8,339)			(8,339)
Balance, at Sep. 26, 2020	$ 9,949	$ 1,272,655	$ 2,959	$ (150,857)	$ 1,134,706
Balance, shares at Sep. 26, 2020	33,047,807			6,149,364