Product Warranty Reserves (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Product Warranties Disclosures [Abstract]
Product warranty reserve at beginning of period	$ 2,115	$ 2,210	$ 2,214	$ 1,850
Warranty reserve assumed in business combination	0	0	0	209
Warranty liabilities accrued	1,430	1,180	4,707	3,372
Warranty liabilities settled	(1,880)	(1,266)	(6,682)	(3,715)
Changes for pre-existing warranty liabilities	616	204	2,042	612
Product warranty reserve at end of period	$ 2,281	$ 2,328	$ 2,281	$ 2,328