CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Cumulative-effect adjustment	Adjusted Balance	Common Stock	Common Stock Adjusted Balance	Retained Earnings	Retained Earnings Cumulative-effect adjustment	Retained Earnings Adjusted Balance	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Adjusted Balance
Beginning balance at Dec. 29, 2018	$ 196,472			$ 22,837		$ 186,229			$ (12,594)
Beginning balance (in shares) at Dec. 29, 2018				8,010,480
Increase (Decrease) in Shareholders' Equity
Net income	4,665					4,665
Foreign currency translation adjustment	712								712
Exercise of stock options	1,526			$ 1,526
Exercise of stock options (in shares)				64,700
Share-based compensation expense	911			$ 911
Restricted shares vesting (in shares)				25,484
Redemption of vested employee restricted shares for tax withholding	(388)			$ (388)
Redemption of vested employee restricted shares for tax withholding (in shares)				(8,157)
Shares repurchased	(4,349)			$ (4,349)
Shares repurchased (in shares)				(86,609)
Accrued dividends on unvested shares	8					8
Cash paid on dividend equivalents	(35)					(35)
Cash dividends paid to shareholders (per share)	(1,616)					(1,616)
Ending balance at Mar. 30, 2019	197,890			$ 20,537		189,235			(11,882)
Ending balance (in shares) at Mar. 30, 2019				8,005,898
Beginning balance at Dec. 29, 2018	196,472			$ 22,837		186,229			(12,594)
Beginning balance (in shares) at Dec. 29, 2018				8,010,480
Increase (Decrease) in Shareholders' Equity
Net income	15,984
Foreign currency translation adjustment	(1,429)
Ending balance at Sep. 28, 2019	192,352			$ 9,028		197,347			(14,023)
Ending balance (in shares) at Sep. 28, 2019				7,707,886
Beginning balance at Mar. 30, 2019	197,890			$ 20,537		189,235			(11,882)
Beginning balance (in shares) at Mar. 30, 2019				8,005,898
Increase (Decrease) in Shareholders' Equity
Net income	5,580					5,580
Foreign currency translation adjustment	(653)								(653)
Share-based compensation expense	848			$ 848
Restricted shares vesting (in shares)				513
Shares repurchased	(7,161)			$ (7,161)
Shares repurchased (in shares)				(177,101)
Accrued dividends on unvested shares	44					44
Cash paid on dividend equivalents	(1,580)					(1,580)
Ending balance at Jun. 29, 2019	194,880			$ 14,224		193,191			(12,535)
Ending balance (in shares) at Jun. 29, 2019				7,829,310
Increase (Decrease) in Shareholders' Equity
Net income	5,739					5,739
Foreign currency translation adjustment	(1,488)								(1,488)
Exercise of stock options	480			$ 480
Exercise of stock options (in shares)				21,224
Share-based compensation expense	882			$ 882
Restricted shares vesting (in shares)				14,754
Shares repurchased	(6,558)			$ (6,558)
Shares repurchased (in shares)				(157,402)
Accrued dividends on unvested shares	37					37
Cash dividends paid to shareholders (per share)	(1,546)					(1,546)
Ending balance at Sep. 28, 2019	192,352			$ 9,028		197,347			(14,023)
Ending balance (in shares) at Sep. 28, 2019				7,707,886
Beginning balance at Dec. 28, 2019	$ 197,751	$ (203)	$ 197,548	$ 9,265	$ 9,265	200,249	$ (203)	$ 200,046	(11,763)	$ (11,763)
Beginning balance (in shares) at Dec. 28, 2019	7,814,797			7,814,797	7,814,797
Increase (Decrease) in Shareholders' Equity
Net income	$ 6,468					6,468
Foreign currency translation adjustment	(2,427)								(2,427)
Exercise of stock options	151			$ 151
Exercise of stock options (in shares)				8,200
Share-based compensation expense	655			$ 655
Restricted shares vesting (in shares)				23,884
Redemption of vested employee restricted shares for tax withholding	(390)			$ (390)
Redemption of vested employee restricted shares for tax withholding (in shares)				(7,843)
Shares repurchased	(3,810)			$ (3,810)
Shares repurchased (in shares)				(82,613)
Accrued dividends on unvested shares	(1)					(1)
Cash paid on dividend equivalents	(40)					(40)
Cash dividends paid to shareholders (per share)	(1,796)					(1,796)
Ending balance at Mar. 28, 2020	196,360			$ 5,871		204,679			(14,190)
Ending balance (in shares) at Mar. 28, 2020				7,756,425
Beginning balance at Dec. 28, 2019	$ 197,751	$ (203)	$ 197,548	$ 9,265	$ 9,265	200,249	$ (203)	$ 200,046	(11,763)	$ (11,763)
Beginning balance (in shares) at Dec. 28, 2019	7,814,797			7,814,797	7,814,797
Increase (Decrease) in Shareholders' Equity
Net income	$ 17,802
Foreign currency translation adjustment	(302)
Ending balance at Sep. 26, 2020	$ 204,395			$ 4,092		212,368			(12,065)
Ending balance (in shares) at Sep. 26, 2020	7,739,550			7,739,550
Beginning balance at Mar. 28, 2020	$ 196,360			$ 5,871		204,679			(14,190)
Beginning balance (in shares) at Mar. 28, 2020				7,756,425
Increase (Decrease) in Shareholders' Equity
Net income	5,931					5,931
Foreign currency translation adjustment	536								536
Exercise of stock options	418			$ 418
Exercise of stock options (in shares)				22,611
Share-based compensation expense	796			$ 796
Restricted shares vesting (in shares)				513
Accrued dividends on unvested shares	38					38
Cash paid on dividend equivalents	(1,788)					(1,788)
Ending balance at Jun. 27, 2020	202,215			$ 7,085		208,784			(13,654)
Ending balance (in shares) at Jun. 27, 2020				7,779,549
Increase (Decrease) in Shareholders' Equity
Net income	5,403					5,403
Foreign currency translation adjustment	1,589								1,589
Exercise of stock options	1,098			$ 1,098
Exercise of stock options (in shares)				57,219
Share-based compensation expense	906			$ 906
Restricted shares vesting (in shares)				12,936
Shares repurchased	(4,997)			$ (4,997)
Shares repurchased (in shares)				(110,154)
Accrued dividends on unvested shares	31					31
Cash paid on dividend equivalents	(1,788)					(1,788)
Ending balance at Sep. 26, 2020	$ 204,395			$ 4,092		$ 212,368			$ (12,065)
Ending balance (in shares) at Sep. 26, 2020	7,739,550			7,739,550