CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Earnings	Noncontrolling Interest	Total
Beginning balance at Dec. 26, 2015	$ 20,142	$ 171,562	$ 565,636	$ (4,585)	$ 13,654	$ 766,409
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings			19,212		1,043	20,255
Foreign currency translation adjustment				666	(197)	469
Unrealized gain (loss) on investment				(27)		(27)
Distributions to noncontrolling interest					(1,170)	(1,170)
Issuance of 1,738 and 1,850 shares under employee stock plans (periods ending April 1, 2017 and March 26, 2016, respectively)	2	128				130
Issuance of 135,776 and 114,739 shares under stock grant programs (periods ending April 1, 2017 and March 26, 2016, respectively)	114	5,118				5,232
Issuance of 39,346 and 42,786 shares under deferred compensation plans (periods ending April 1, 2017 and March 26, 2016, respectively)	43	(43)
Expense associated with share-based compensation arrangements		432				432
Accrued expense under deferred compensation plans		3,198				3,198
Ending balance at Mar. 26, 2016	20,301	180,395	584,848	(3,946)	13,330	794,928
Beginning balance at Dec. 31, 2016	20,342	185,333	649,135	(5,630)	11,286	860,466
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings			21,062		572	21,634
Foreign currency translation adjustment				1,971	855	2,826
Unrealized gain (loss) on investment				209		209
Distributions to noncontrolling interest					(1,673)	(1,673)
Additional purchases of noncontrolling interest					1,774	1,774
Issuance of 1,738 and 1,850 shares under employee stock plans (periods ending April 1, 2017 and March 26, 2016, respectively)	2	144				146
Issuance of 135,776 and 114,739 shares under stock grant programs (periods ending April 1, 2017 and March 26, 2016, respectively)	136	7,107				7,243
Issuance of 39,346 and 42,786 shares under deferred compensation plans (periods ending April 1, 2017 and March 26, 2016, respectively)	39	(39)
Repurchase of 880 shares	(1)		(82)			(83)
Expense associated with share-based compensation arrangements		571				571
Accrued expense under deferred compensation plans		4,240				4,240
Ending balance at Apr. 01, 2017	$ 20,518	$ 197,356	$ 670,115	$ (3,450)	$ 12,814	$ 897,353