Intangible assets, net (Details) (USD $)	6 Months Ended
	Jun. 28, 2013	Jun. 27, 2014	Dec. 27, 2013
Finite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization (definite lives)		$ 5,300,000	$ 5,300,000
Accumulated amortization		(5,300,000)	(5,300,000)
Net intangible assets subject to amortization		0	0
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, net		2,040,000	2,040,000
Amortization expense for period	200,000
Trade Name [Member]
Indefinite-lived Intangible Assets [Line Items]
Intangible assets not subject to amortization (indefinite lives)		2,040,000	2,040,000
Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization (definite lives)		3,300,000	3,300,000
Accumulated amortization		(3,300,000)	(3,300,000)
Technology [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization (definite lives)		2,000,000	2,000,000
Accumulated amortization		$ (2,000,000)	$ (2,000,000)