Condensed Consolidated Statements of Comprehensive Loss (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2014	Mar. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (3,347)	$ (12,103)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	285	(4,002)
Adjustments related to postretirement benefits	44	59
Change in unrealized gain/loss on investments		(3)
Other comprehensive income (loss), net of tax	329	(3,946)
Comprehensive loss	$ (3,018)	$ (16,049)