CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 28, 2013	Jun. 29, 2012	Jun. 28, 2013	Jun. 29, 2012
Statement Of Partners Capital [Abstract]
Net income (loss)	$ (3,800)	$ 17	$ 2,621	$ (7,511)
Other comprehensive income (loss), net of tax:
Changes in cumulative translation adjustments	154	(400)	(470)	(86)
Foreign currency translation adjustments	154	(400)	(470)	(86)
Changes in unrealized gain (loss) on investment arising during the period	(46)	(14)	(41)	25
Gain (loss) on investments	(46)	(14)	(41)	25
Other comprehensive income (loss) before tax	108	(414)	(511)	(61)
Income tax benefit related to items of other comprehensive income (loss)	(9)	(29)	(12)	(14)
Other comprehensive income (loss), net of tax	117	(385)	(499)	(47)
Comprehensive income (loss)	$ (3,683)	$ (368)	$ 2,122	$ (7,558)