Business Combinations - Income Statement (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	Jun. 28, 2015	Jun. 30, 2016	Jun. 28, 2015
Business Acquisition
Net sales		$ 98,693	$ 100,071	$ 195,398	$ 198,382
Net loss		$ 14,487	$ 19,080	$ 22,350	$ 25,367
CTG Advanced
Business Acquisition
Net sales	$ 3,876
Net loss	$ 111