Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2013	Dec. 29, 2012
Summary of Finite-lived intangible assets
Adjusted cost	$ 31,765	$ 31,497
Accumulated amortization	(23,206)	(20,517)
Net carrying amount	8,559	10,980
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	17,948	17,700
Accumulated amortization	(10,313)	(8,277)
Net carrying amount	7,635	9,423
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,558	9,538
Accumulated amortization	(9,166)	(8,643)
Net carrying amount	392	895
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,675)	(1,599)
Net carrying amount	252	328
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(1,972)	(1,922)
Net carrying amount	280	330
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(80)	(76)
Net carrying amount	$ 0	$ 4