Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 27, 2015	Dec. 27, 2014
Summary of Finite-lived intangible assets
Adjusted cost	$ 29,917	$ 30,670
Accumulated amortization	(27,031)	(26,376)
Net carrying amount	2,886	4,294
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	16,278	16,950
Accumulated amortization	(13,632)	(12,991)
Net carrying amount	2,646	3,959
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,380	9,461
Accumulated amortization	(9,380)	(9,449)
Net carrying amount	0	12
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,852)	(1,802)
Net carrying amount	75	125
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(2,087)	(2,054)
Net carrying amount	165	198
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(80)	(80)
Net carrying amount	$ 0	$ 0