Current Liabilities - Warranty Accrual (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Accounts Payable and Accrued Liabilities, Current [Abstract]
New product warranty period			12 months
Refurbished product warranty period			3 months
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance, beginning of the period	$ 1,737	$ 1,055	$ 1,501	$ 1,142
Liabilities accrued for warranties issued	448	396	1,063	678
Warranty claims paid and utilized	(489)	(524)	(1,118)	(1,002)
Changes in accrued warranty liabilities	70	156	320	265
Balance, end of the period	$ 1,766	$ 1,083	$ 1,766	$ 1,083