Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 15,932	$ 14,046	$ 12,404	$ 10,035
Components of other comprehensive income/(loss), net of tax:
Foreign currency translation adjustments	(84)	971	(2,267)	(3)
Amortization of defined benefit pension items:
Net actuarial loss	215	110	455	220
Prior service cost	0	2	2	4
Defined benefit pension plan adjustments	215	112	457	224
Other comprehensive income/(loss), net of tax	131	1,083	(1,810)	221
Comprehensive income	$ 16,063	$ 15,129	$ 10,594	$ 10,256