Business Realignment and Restructuring (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 36	$ 567		$ 256	$ 2,195
Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense				2,329	2,894
Particulate Matter Product Line Strategic Exit [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	675	342		2,329	2,894
Particulate Matter Product Line Strategic Exit [Member] \| Control Devices [Member] \| Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	1,400			1,400
Particulate Matter Product Line Strategic Exit [Member] \| Control Devices [Member] \| Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	4,200			4,200
Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			$ 13	13	2,881
Canton Facility Restructuring Plan [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	0	197
Employee Termination [Member] \| Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense				50	961
Employee Termination [Member] \| Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense				139
Employee Termination [Member] \| Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense					1,119
Fixed Asset Impairment [Member] \| Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense					2,824
Other Restructuring [Member] \| Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense				206	782
Other Restructuring [Member] \| Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense				2,002	70
Other Restructuring [Member] \| Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense			$ 13		1,762
Contract Termination [Member] \| Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense					452
Selling, General and Administrative Expenses [Member] \| Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	2	383		176	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	(31)	2		642	2,391
Selling, General and Administrative Expenses [Member] \| Canton Facility Restructuring Plan [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense					549
Cost of Goods Sold [Member] \| Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	34	132		37	132
Cost of Goods Sold [Member] \| Particulate Matter Product Line Strategic Exit [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	605	340		1,505	503
Cost of Goods Sold [Member] \| Canton Facility Restructuring Plan [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		88			1,659
Design and Development Expense [Member] \| Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		52		43	429
Design and Development Expense [Member] \| Particulate Matter Product Line Strategic Exit [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 101			182
Design and Development Expense [Member] \| Canton Facility Restructuring Plan [Member] \| Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 109		$ 13	$ 673