Business Realignment and Restructuring (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 567	$ 157	$ 2,195	$ 469
Additional restructuring costs	500		500
Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			2,894
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	342		2,894
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member] | Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	1,335		1,335
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member] | Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	4,015		4,015
Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			2,881	9,275
Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	197	3,607	2,881	9,275
Estimated total cost	300		300
Employee Termination [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			961	(30)
Employee Termination [Member] | Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			1,119	6,967
Other Restructuring [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			782	186
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			1,762	2,308
Contract Termination [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			452	24
Selling, General and Administrative Expenses [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	383		1,634
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		2,391
Selling, General and Administrative Expenses [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	0
Selling, General and Administrative Expenses [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		287	549	762
Cost of Goods Sold [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	132		132
Cost of Goods Sold [Member] | Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	340		503
Cost of Goods Sold [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	88
Cost of Goods Sold [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		2,567	1,659	6,173
Design and Development Expense [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	52		429
Design and Development Expense [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 109
Design and Development Expense [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 753	$ 673	$ 2,340