Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 26, 2015	Dec. 27, 2014
Summary of Finite-lived intangible assets
Adjusted cost	$ 29,721	$ 30,670
Accumulated amortization	(27,854)	(26,376)
Finite lived intangible assets, Net carrying amount	1,867	4,294
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	16,098	16,950
Accumulated amortization	(14,387)	(12,991)
Finite lived intangible assets, Net carrying amount	1,711	3,959
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,364	9,461
Accumulated amortization	(9,364)	(9,449)
Finite lived intangible assets, Net carrying amount	0	12
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,903)	(1,802)
Finite lived intangible assets, Net carrying amount	24	125
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(2,120)	(2,054)
Finite lived intangible assets, Net carrying amount	132	198
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(80)	(80)
Finite lived intangible assets, Net carrying amount	$ 0	$ 0