Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (493)	$ (6,627)
Components of other comprehensive income/(loss), net of tax:
Foreign currency translation adjustments	509	(832)
Amortization of defined benefit pension items:
Net actuarial loss	32	134
Prior service cost	12	12
Defined benefit pension plan adjustments	44	146
Other comprehensive income/(loss), net of tax	553	(686)
Comprehensive income/(loss)	$ 60	$ (7,313)