Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands		Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Noncontrolling Interest [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (Accounting Standards Update 2016-02 [Member]) at Dec. 29, 2018	[1]	$ 0	$ 0	$ 10,352	$ 0	$ 0	$ 10,352
Balance at Dec. 29, 2018								$ 40,763	$ 419,690	$ 111,670	$ (25,880)	$ (299)	$ 545,944
Net income (loss)								0	0	(42,046)	0	0	(42,046)
Changes in cumulative translation adjustment								0	0	0			(1,578)
Changes in cumulative translation adjustment, attributable to parent											(1,574)		(1,578)
Changes in cumulative translation adjustment, attributable to non-controlling interest												(4)
Shares issued under ESPP								64	743	0	0	0	807
Shares issued for restricted stock units vested								394	(394)	0	0	0	0
Repurchase and retirement of stock								(136)	(1,892)	0	0	0	(2,028)
Share-based compensation expense								0	7,355	0	0	0	7,355
Cash dividends								0	0	(4,914)	0	0	(4,914)
Exercise of stock options								15	107	0	0	0	122
Adjustments related to postretirement benefits, net of tax								0	0	0	435	0	435
Noncontrolling interest								0	0	53	0	(53)	0
Balance at Jun. 29, 2019								41,100	425,609	75,115	(27,019)	(356)	514,449
Balance at Mar. 30, 2019								41,015	421,381	96,938	(30,664)	(356)	528,314
Net income (loss)								0	0	(19,359)	0	0	(19,359)
Changes in cumulative translation adjustment								0	0	0			3,684
Changes in cumulative translation adjustment, attributable to parent											3,684		3,684
Changes in cumulative translation adjustment, attributable to non-controlling interest												0
Shares issued under ESPP								64	743	0	0	0	807
Shares issued for restricted stock units vested								29	(29)	0	0	0	0
Repurchase and retirement of stock								(13)	(187)	0	0	0	(200)
Share-based compensation expense								0	3,662	0	0	0	3,662
Cash dividends								0	0	(2,464)	0	0	(2,464)
Exercise of stock options								5	39	0	0	0	44
Adjustments related to postretirement benefits, net of tax								0	0	0	(39)	0	(39)
Balance at Jun. 29, 2019								41,100	425,609	75,115	(27,019)	(356)	514,449
Balance at Dec. 28, 2019								41,395	433,190	42,517	(34,030)	0	483,072
Net income (loss)								0	0	(22,016)	0	0	(22,016)
Changes in cumulative translation adjustment								0	0	0			968
Changes in cumulative translation adjustment, attributable to parent											968		968
Changes in cumulative translation adjustment, attributable to non-controlling interest												0
Shares issued under ESPP								114	1,488	0	0	0	1,602
Shares issued for restricted stock units vested								487	(487)	0	0	0	0
Repurchase and retirement of stock								(156)	(1,529)	0	0	0	(1,685)
Share-based compensation expense								0	7,014	0	0	0	7,014
Cash dividends								0	0	(2,486)	0	0	(2,486)
Exercise of stock options								22	267	0	0	0	289
Adjustments related to postretirement benefits, net of tax													0
Balance at Jun. 27, 2020								41,862	439,943	18,015	(33,062)	0	466,758
Balance at Mar. 28, 2020								41,686	435,402	22,755	(34,959)	0	464,884
Net income (loss)								0	0	(4,740)	0	0	(4,740)
Changes in cumulative translation adjustment								0	0	0			1,897
Changes in cumulative translation adjustment, attributable to parent											1,897		1,897
Changes in cumulative translation adjustment, attributable to non-controlling interest												0
Shares issued under ESPP								114	1,488	0	0	0	1,602
Shares issued for restricted stock units vested								84	(84)	0	0	0	0
Repurchase and retirement of stock								(22)	(266)	0	0	0	(288)
Share-based compensation expense								0	3,403	0	0	0	3,403
Adjustments related to postretirement benefits, net of tax													0
Balance at Jun. 27, 2020								$ 41,862	$ 439,943	$ 18,015	$ (33,062)	$ 0	$ 466,758

[1] Cumulative effect of accounting change relates to our adoption of ASU 2016-02. Please refer to Note 1 of the Condensed Consolidated Financial Statements for further detail on the adoption of this accounting standard.