Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common stock $1 par value	Paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)
Beginning balance at Dec. 27, 2008	$ 285,539	$ 23,344	$ 61,076	$ 193,985	$ 7,134
Components of comprehensive income (loss):
Net income (loss)	(28,168)			(28,168)
Changes in cumulative translation adjustment	1,538				1,538
Adjustments related to postretirement benefits, net of income taxes	(444)				(444)
Changes in unrealized gains and losses on investments, net of income taxes	434				434
Comprehensive income (loss)	(26,640)
Cash dividends - $0.24 per share	(5,624)			(5,624)
Shares issued under employee stock purchase plan	1,128	136	992
Shares issued for restricted stock units vested		102	(102)
Repurchase and retirement of stock	(419)	(35)	(384)
Share-based compensation expense	3,378		3,378
Tax benefit (deficiency) from equity awards	(113)		(113)
Ending balance at Dec. 26, 2009	257,249	23,547	64,847	160,193	8,662
Components of comprehensive income (loss):
Net income (loss)	24,644			24,644
Changes in cumulative translation adjustment	(7,270)				(7,270)
Adjustments related to postretirement benefits, net of income taxes	(1,506)				(1,506)
Changes in unrealized gains and losses on investments, net of income taxes	(83)				(83)
Comprehensive income (loss)	15,785
Cash dividends - $0.24 per share	(5,703)			(5,703)
Exercise of stock options	2,869	263	2,606
Shares issued under employee stock purchase plan	1,213	112	1,101
Shares issued for restricted stock units vested		101	(101)
Repurchase and retirement of stock	(465)	(34)	(431)
Share-based compensation expense	3,543		3,543
Tax benefit (deficiency) from equity awards	234		234
Ending balance at Dec. 25, 2010	274,725	23,989	71,799	179,134	(197)
Components of comprehensive income (loss):
Net income (loss)	15,719			15,719
Changes in cumulative translation adjustment	(1,076)				(1,076)
Adjustments related to postretirement benefits, net of income taxes	1,267				1,267
Changes in unrealized gains and losses on investments, net of income taxes	(6)				(6)
Comprehensive income (loss)	15,904
Cash dividends - $0.24 per share	(5,798)			(5,798)
Exercise of stock options	1,111	123	988
Shares issued under employee stock purchase plan	1,262	120	1,142
Shares issued for restricted stock units vested		139	(139)
Repurchase and retirement of stock	(462)	(41)	(421)
Share-based compensation expense	4,287		4,287
Tax benefit (deficiency) from equity awards	2		2
Ending balance at Dec. 31, 2011	$ 291,031	$ 24,330	$ 77,658	$ 189,055	$ (12)