Business Realignment and Restructuring (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 199	$ 7
Additional restructuring costs	660
Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	1,369
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	1,369
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member] | Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	800
Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member] | Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated total cost	3,600
Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	13	2,222
Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	13	2,222
Employee Termination [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	53
Employee Termination [Member] | Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	76
Employee Termination [Member] | Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		1,118
Other Restructuring [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	146	7
Other Restructuring [Member] | Particulate Matter Product Line Strategic Exit [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	1,108
Other Restructuring [Member] | Canton Facility Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	13	1,104
Selling, General and Administrative Expenses [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	155
Selling, General and Administrative Expenses [Member] | Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	638
Selling, General and Administrative Expenses [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		314
Cost of Goods Sold [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	(2)
Cost of Goods Sold [Member] | Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	650
Cost of Goods Sold [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		1,490
Design and Development Expense [Member] | Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	46
Design and Development Expense [Member] | Particulate Matter Product Line Strategic Exit [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	81
Design and Development Expense [Member] | Canton Facility Restructuring Plan [Member] | Canton Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 13
Design and Development Expense [Member] | Canton Facility Restructuring Plan [Member] | Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 418