Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock $1 Par Value [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2011	$ 291,031	$ 24,330	$ 77,658	$ 189,055	$ (12)
Net income (loss)	(12,243)			(12,243)
Changes in cumulative translation adjustment	1,689				1,689
Adjustments related to postretirement benefits, net of tax	122				122
Changes in unrealized gains and losses on investments, net of tax	(16)				(16)
Cash dividends - $0.24 per share	(5,875)			(5,875)
Exercise of stock options	609	73	536
Shares issued under employee stock purchase plan	1,252	152	1,100
Shares issued for restricted stock units vested		108	(108)
Repurchase and retirement of stock	(291)	(31)	(260)
Share-based compensation expense	4,621		4,621
Ending balance at Dec. 29, 2012	280,899	24,632	83,547	170,937	1,783
Net income (loss)	(33,418)			(33,418)
Changes in cumulative translation adjustment	3,270				3,270
Adjustments related to postretirement benefits, net of tax	1,604				1,604
Changes in unrealized gains and losses on investments, net of tax	(6)				(6)
Cash dividends - $0.24 per share	(5,973)			(5,973)
Exercise of stock options	886	117	769
Shares issued under employee stock purchase plan	1,251	163	1,088
Shares issued for restricted stock units vested		249	(249)
Repurchase and retirement of stock	(821)	(81)	(740)
Share-based compensation expense	5,468		5,468
Ending balance at Dec. 28, 2013	253,160	25,080	89,883	131,546	6,651
Net income (loss)	8,708			8,708
Changes in cumulative translation adjustment	(14,107)				(14,107)
Adjustments related to postretirement benefits, net of tax	(3,258)				(3,258)
Cash dividends - $0.24 per share	(6,102)			(6,102)
Exercise of stock options	2,001	237	1,764
Shares issued under employee stock purchase plan	1,140	139	1,001
Shares issued for restricted stock units vested		353	(353)
Repurchase and retirement of stock	(1,250)	(117)	(1,133)
Share-based compensation expense	6,776		6,776
Ending balance at Dec. 27, 2014	$ 247,068	$ 25,692	$ 97,938	$ 134,152	$ (10,714)