Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Mar. 30, 2013	Dec. 29, 2012
Summary of Finite-lived intangible assets
Adjusted cost	$ 31,251	$ 31,497
Accumulated amortization	(21,313)	(20,517)
Net carrying amount	9,938	10,980
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	17,482	17,700
Accumulated amortization	(8,871)	(8,277)
Net carrying amount	8,611	9,423
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,510	9,538
Accumulated amortization	(8,800)	(8,643)
Net carrying amount	710	895
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,625)	(1,599)
Net carrying amount	302	328
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(1,939)	(1,922)
Net carrying amount	313	330
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(78)	(76)
Net carrying amount	$ 2	$ 4