Revenues Revenues (Disaggregation of Revenue by Market Sector) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 69,142	$ 67,421	$ 70,870	$ 76,525	$ 76,982	$ 75,490	$ 74,231	$ 73,091	$ 283,958	$ 299,794	$ 254,350
Test & Measurement
Disaggregation of Revenue [Line Items]
Revenue									69,594	76,735	64,798
Avionics, Military & Space
Disaggregation of Revenue [Line Items]
Revenue									23,975	26,743	22,378
Medical
Disaggregation of Revenue [Line Items]
Revenue									10,863	9,868	8,769
Precision Weighing
Disaggregation of Revenue [Line Items]
Revenue									91,001	93,734	81,439
Force Measurement
Disaggregation of Revenue [Line Items]
Revenue									55,648	66,551	53,503
Steel
Disaggregation of Revenue [Line Items]
Revenue									$ 32,877	$ 26,163	$ 23,463