Goodwill and Intangible Assets (Finite-lived Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Summary of Finite-lived intangible assets
Adjusted cost	$ 31,240	$ 31,927
Accumulated amortization	(25,985)	(24,063)
Net carrying amount	5,255	7,864
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	17,471	18,095
Accumulated amortization	(12,647)	(11,032)
Net carrying amount	4,824	7,063
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,510	9,573
Accumulated amortization	(9,444)	(9,263)
Net carrying amount	66	310
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,776)	(1,700)
Net carrying amount	151	227
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(2,038)	(1,988)
Net carrying amount	214	264
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(80)	(80)
Net carrying amount	$ 0	$ 0