Warranties (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2015	Jun. 28, 2014	Jun. 27, 2015	Jun. 28, 2014
Components of the warranty accrual [Roll Forward]
Balance as of beginning of period	$ 3,440	$ 3,575	$ 2,953	$ 3,426
Accruals for warranties issued during period	2,251	1,906	3,953	3,217
Settlements during the period	(1,899)	(1,997)	(3,114)	(3,159)
Balance as of end of period	$ 3,792	$ 3,484	$ 3,792	$ 3,484