Goodwill and Intangible Assets (Finite-lived Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 29, 2014	Dec. 28, 2013
Summary of Finite-lived intangible assets
Adjusted cost	$ 32,040	$ 31,927
Accumulated amortization	(24,901)	(24,063)
Net carrying amount	7,139	7,864
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	18,197	18,095
Accumulated amortization	(11,738)	(11,032)
Net carrying amount	6,459	7,063
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,584	9,573
Accumulated amortization	(9,352)	(9,263)
Net carrying amount	232	310
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,726)	(1,700)
Net carrying amount	201	227
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(2,005)	(1,988)
Net carrying amount	247	264
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(80)	(80)
Net carrying amount	$ 0	$ 0