CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (4,045)	$ (2,109)	$ (16,148)	$ (5,333)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	1,130	(4,995)	(2,872)	(2,412)
Adjustments related to postretirement benefits	31	44	90	76
Change in unrealized gain/loss on investments	(4)	(13)	(7)	(1)
Other comprehensive income (loss), net of tax	1,157	(4,964)	(2,789)	(2,337)
Comprehensive loss	$ (2,888)	$ (7,073)	$ (18,937)	$ (7,670)