Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 29, 2012	$ 24,632	$ 83,547	$ 170,937	$ 1,783	$ 280,899
Net 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	$ 117	$ 769			886
Shares issued under employee stock purchase plan	163	1,088			$ 1,251
Shares issued for restricted stock units vested	249	(249)
Repurchase and retirement of stock	$ (81)	(740)			$ (821)
Share-based compensation expense		5,468			5,468
Balance at Dec. 28, 2013	$ 25,080	$ 89,883	$ 131,546	$ 6,651	253,160
Net 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)
Changes in unrealized gains and losses on investments, net of tax
Cash dividends - $0.24 per share			$ (6,102)		$ (6,102)
Exercise of stock options	$ 237	$ 1,764			2,001
Shares issued under employee stock purchase plan	139	1,001			$ 1,140
Shares issued for restricted stock units vested	353	(353)
Repurchase and retirement of stock	$ (117)	(1,133)			$ (1,250)
Share-based compensation expense		6,776			6,776
Balance at Dec. 27, 2014	$ 25,692	$ 97,938	$ 134,152	$ (10,714)	247,068
Net loss			$ 250		250
Changes in cumulative translation adjustment				$ (11,000)	(11,000)
Adjustments related to postretirement benefits, net of tax				$ (58)	$ (58)
Changes in unrealized gains and losses on investments, net of tax
Cash dividends - $0.24 per share			$ (6,249)		$ (6,249)
Exercise of stock options	$ 175	$ 1,335			1,510
Shares issued under employee stock purchase plan	123	977			$ 1,100
Shares issued for restricted stock units vested	377	(377)
Repurchase and retirement of stock	$ (127)	(1,250)			$ (1,377)
Share-based compensation expense		6,893			6,893
Balance at Dec. 26, 2015	$ 26,240	$ 105,516	$ 128,153	$ (21,772)	$ 238,137