Business Realignment and Restructuring (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 1,621		$ 1,628	$ 312
Additional restructuring costs	4,950		4,950
Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			2,552
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	2,552		2,552
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member] | Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	1,550		1,550
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member] | Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	4,650		4,650
Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			2,683	5,668
Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	461	$ 3,443	2,683	5,668
Estimated total cost	600		600
Employee Termination [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			863	(30)
Employee Termination [Member] | Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			1,119	4,603
Other Restructuring [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			313	120
Other Restructuring [Member] | Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			70
Other Restructuring [Member] | Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			1,564	1,065
Contract Termination [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			452	27
Selling, General and Administrative Expenses [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	1,244	96	1,251	312
Selling, General and Administrative Expenses [Member] | Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	2,388		2,388
Selling, General and Administrative Expenses [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	235
Selling, General and Administrative Expenses [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		280	549	475
Cost of Goods Sold [Member] | Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	164		164
Cost of Goods Sold [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	80
Cost of Goods Sold [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		2,354	1,570	3,606
Design and Development Expense [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	377		377
Design and Development Expense [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 146
Design and Development Expense [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 809	$ 564	$ 1,587