Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]		Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 28, 2013	$ 25,080,000	$ 89,883,000		$ 131,546,000	$ 6,651,000	$ 253,160,000
Net income				8,708,000		8,708,000
Changes in cumulative translation adjustment					(14,107,000)	(14,107,000)
Adjustments related to postretirement benefits, net of tax					(3,258,000)	(3,258,000)
Cash dividends - $0.24 per share				(6,102,000)		(6,102,000)
Exercise of stock options	237,000	1,764,000				2,001,000
Shares issued under employee stock purchase plan	139,000	1,001,000				1,140,000
Shares issued for restricted stock units vested	353,000	(353,000)
Repurchase and retirement of stock	(117,000)	(1,133,000)				(1,250,000)
Share-based compensation expense		6,776,000				6,776,000
Balance at Dec. 27, 2014	25,692,000	97,938,000		134,152,000	(10,714,000)	247,068,000
Change in unrealized gain/loss on investments, net of tax
Net income				250,000		250,000	[1]
Changes in cumulative translation adjustment					(11,000,000)	(11,000,000)
Adjustments related to postretirement benefits, net of tax					(58,000)	(58,000)
Cash dividends - $0.24 per share				(6,249,000)		(6,249,000)
Exercise of stock options	175,000	1,335,000				1,510,000
Shares issued under employee stock purchase plan	123,000	977,000				1,100,000
Shares issued for restricted stock units vested	377,000	(377,000)
Repurchase and retirement of stock	(127,000)	(1,250,000)				(1,377,000)
Share-based compensation expense		6,893,000				6,893,000
Balance at Dec. 26, 2015	26,240,000	105,516,000		128,153,000	(21,772,000)	238,137,000
Change in unrealized gain/loss on investments, net of tax
Net income				3,039,000		3,039,000	[1],[2]
Changes in cumulative translation adjustment					(5,789,000)	(5,789,000)
Adjustments related to postretirement benefits, net of tax					(316,000)	(316,000)
Cash dividends - $0.24 per share				(6,384,000)		(6,384,000)
Exercise of stock options	101,000	694,000				795,000
Shares issued under employee stock purchase plan	111,000	959,000				1,070,000
Shares issued for restricted stock units vested	581,000	(581,000)
Repurchase and retirement of stock	(191,000)	(2,030,000)				(2,221,000)
Share-based compensation expense		7,143,000				7,143,000
Balance at Dec. 31, 2016	26,842,000	111,950,000		124,559,000	(27,882,000)	235,469,000
Change in unrealized gain/loss on investments, net of tax					$ (5,000)	(5,000)
Cumulative effect of accounting change (a) | Adjustments for New Accounting Principle, Early Adoption [Member]		$ 249,000	[3]	$ (249,000)		$ 200,000

[1] All quarters presented above were comprised of 13 weeks, except for the fourth quarter ended December 31, 2016 which was comprised of 14 weeks.

[2] As a result of the adoption of ASU 2016-09, in the fourth quarter of 2016, certain amounts in the first three quarters have been restated as if the new accounting guidance was adopted starting with the first day of our 2016 fiscal year. The impact of these restatements was not significant.

[3] Cumulative effect of accounting change relates to our adoption of ASU 2016-09. Please refer to Note 1 of the Consolidated Financial Statements for further detail on the adoption of this accounting standard.