CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 5,080	$ 3,568
Other comprehensive earnings/(loss):
Cumulative translation adjustment, net of tax benefit of $71 and net of tax of $534	204	(1,741)
Defined benefit and post-retirement benefit plans:
Amortization of prior service cost included in net periodic pension costs, net of tax of $0 and $59		91
Amortization of loss included in net periodic pension costs, net of tax of $536 and $774	897	1,245
Foreign exchange impact, net of tax of $0 and $74	17	207
Reclassification adjustments included in net earnings-defined benefit and post-retirement benefit plans	914	1,543
Unrealized gain on interest swaps treated as cash flow hedges:
Unrealized holding (losses)/gains arising during period, net of tax benefit of $21 and net of tax of $14	(33)	22
Reclassification adjustments for losses included in net earnings, net of tax of $45 and $30	73	47
Net change in unrealized holding loss on interest rate swaps	40	69
Other comprehensive earnings/(loss)	1,158	(129)
Comprehensive earnings	$ 6,238	$ 3,439