Segment Reporting - Net Sales to External Customers Based Upon Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 26, 2015	Jun. 27, 2015	Mar. 28, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Geographic Reporting Disclosure [Line Items]
Net sales to external customers	$ 91,698	$ 79,600	$ 78,538	$ 75,748	$ 91,327	$ 72,507	$ 83,775	$ 69,939	$ 325,584	$ 317,548	$ 341,826
United States
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									133,924	131,670	124,851
Americas-Other
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									11,815	11,718	14,117
Germany
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									44,041	41,151	50,437
Europe-Other
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									57,710	62,032	69,742
Japan
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									32,530	24,018	32,531
Asia-Other
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									$ 45,564	$ 46,959	$ 50,148