Warranties (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
Components of the warranty accrual [Roll Forward]
Balance as of beginning of period	$ 4,377	$ 3,440	$ 4,504	$ 2,953
Accruals for warranties issued during period	1,368	2,251	2,429	3,953
Settlements during the period	(1,189)	(1,899)	(2,377)	(3,114)
Balance as of end of period	$ 4,556	$ 3,792	$ 4,556	$ 3,792