Consolidated Statements of Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 27, 2014	$ 226	$ 243,844	$ (18,724)	$ (21,126)	$ 519,956	$ 143	$ 724,319
Comprehensive income:
Net income for the year					80,866		80,866
Pension liability adjustments, net				(1,761)			(1,761)
Pension settlement, net				21,124			21,124
Pension and postemployment reclassification adjustments, net				1,530			1,530
Unrealized (loss) on investments				793			793
Foreign currency translation adjustments				(46,231)			(46,231)
Comprehensive income							56,321
Stock-based compensation		7,782					7,782
Withheld			(2,727)				(2,727)
Retirement of treasury stock			18,712		(18,712)
Purchase of common stock	(4)	(1,221)	(30,027)				(31,252)
Stock options exercised	2	9,148					9,150
Cash dividends paid					(24,341)		(24,341)
Balance at Jan. 02, 2016	224	243,844	(32,766)	(45,671)	557,769	143	739,252
Comprehensive income:
Net income for the year					104,488		104,488
Pension liability adjustments, net				(3,673)			(3,673)
Pension settlement, net
Pension and postemployment reclassification adjustments, net				412			412
Unrealized (loss) on investments				(815)			(815)
Foreign currency translation adjustments				(24,832)			(24,832)
Comprehensive income							75,580
Stock-based compensation		7,471					7,471
Withheld			(3,744)				(3,744)
Stock options exercised	4	24,234					24,238
Cash dividends paid					(27,866)		(27,866)
Balance at Dec. 31, 2016	228	291,258	(36,510)	(74,579)	634,391	143	814,931
Comprehensive income:
Net income for the year					119,519		119,519
Pension liability adjustments, net				1,235			1,235
Pension settlement, net
Pension and postemployment reclassification adjustments, net				(88)			(88)
Unrealized (loss) on investments				(974)			(974)
Foreign currency translation adjustments				10,738			10,738
Comprehensive income							130,430
Stock-based compensation		16,315					16,315
Withheld			(4,784)				(4,784)
Stock options exercised	1	2,439					2,440
Cash dividends paid					(31,770)		(31,770)
Non-controlling interest						6	6
Balance at Dec. 30, 2017	$ 229	$ 310,012	$ (41,294)	$ (63,668)	$ 722,140	$ 137	$ 927,556