Business Realignment and Restructuring (Schedule of Business Realignment Charges Classified by Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restructuring Cost and Reserve [Line Items]
Total business realignment charges	$ 27	$ 520	$ 1,162	$ 742
Cost of Goods Sold [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges	27	26	27	26
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges		366	1,125	588
Design and Development Expense [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges		128	10	128
Control Devices [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges	27	128	549	128
Control Devices [Member] | Cost of Goods Sold [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs			27
Control Devices [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs			512
Control Devices [Member] | Design and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs		128	10	128
Electronics [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges		295		295
Severance costs			512
Electronics [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 27			295
PST Segment [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges		97		319
PST Segment [Member] | Cost of Goods Sold [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs		26		26
PST Segment [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs		$ 71		$ 293
Unallocated Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Total business realignment charges			613
Unallocated Corporate [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Severance costs			$ 613