Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 28, 2019	$ 773,584	$ 326	$ 52,605	$ 720,653
Beginning Balance, Shares at Dec. 28, 2019		32,556,263
Exercise of stock options, shares		10
Compensation expense under Incentive Stock Plan	2,718		2,718
Purchase and cancellation of common stock	(5,865)	$ (1)	(177)	(5,687)
Purchase and cancellation of common stock, Shares		(98,329)
Cancellation of non-vested stock, net of issuances	505	$ 1	504
Cancellation of non-vested stock, net of issuances, shares		(11,845)
Other stock-related activity, net of tax	(470)		(244)	(226)
Other stock related activity, net of tax, Shares		(5,686)
Net income	36,660			36,660
Ending Balance at Jun. 27, 2020	807,132	$ 326	55,406	751,400
Ending Balance, Shares at Jun. 27, 2020		32,440,413
Beginning Balance at Mar. 28, 2020	791,375	$ 325	53,454	737,596
Beginning Balance, Shares at Mar. 28, 2020		32,434,665
Compensation expense under Incentive Stock Plan	1,504		1,504
Purchase and cancellation of common stock	(86)	$ (1)	(2)	(83)
Purchase and cancellation of common stock, Shares		(1,620)
Issuance of non-vested stock, net of cancellations	506	$ 2	504
Issuance of non-vested stock, net of cancellations, Shares		10,129
Other stock-related activity, net of tax	(52)		(54)	2
Other stock related activity, net of tax, Shares		(2,761)
Net income	13,885			13,885
Ending Balance at Jun. 27, 2020	807,132	$ 326	55,406	751,400
Ending Balance, Shares at Jun. 27, 2020		32,440,413
Beginning Balance at Dec. 26, 2020	$ 853,559	$ 322	64,085	789,152
Beginning Balance, Shares at Dec. 26, 2020	32,168,740	32,168,740
Exercise of stock options	$ 736		736
Exercise of stock options, shares		17,346
Compensation expense under Incentive Stock Plan	4,491		4,491
Purchase and cancellation of common stock	(31,249)	$ (3)	(549)	(30,697)
Purchase and cancellation of common stock, Shares		(305,031)
Issuance of non-vested stock, net of cancellations	2,493		2,493
Issuance of non-vested stock, net of cancellations, Shares		20,521
Other stock-related activity, net of tax	(1,393)		691	(2,084)
Other stock related activity, net of tax, Shares		(9,686)
Net income	64,348			64,348
Ending Balance at Jun. 26, 2021	$ 892,985	$ 319	71,947	820,719
Ending Balance, Shares at Jun. 26, 2021	31,891,890	31,891,890
Beginning Balance at Mar. 27, 2021	$ 883,811	$ 321	67,596	815,894
Beginning Balance, Shares at Mar. 27, 2021		32,115,528
Exercise of stock options	420		420
Exercise of stock options, shares		5,732
Compensation expense under Incentive Stock Plan	2,380		2,380
Purchase and cancellation of common stock	(27,275)	$ (2)	(480)	(26,793)
Purchase and cancellation of common stock, Shares		(266,871)
Issuance of non-vested stock, net of cancellations	2,493		2,493
Issuance of non-vested stock, net of cancellations, Shares		38,120
Other stock-related activity, net of tax	(462)		(462)
Other stock related activity, net of tax, Shares		(619)
Net income	31,618			31,618
Ending Balance at Jun. 26, 2021	$ 892,985	$ 319	$ 71,947	$ 820,719
Ending Balance, Shares at Jun. 26, 2021	31,891,890	31,891,890