Segment Reporting Net Sales and Operating Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenue, Net	$ 43,517	$ 40,450	$ 127,010	$ 121,110
Operating Income (Loss)	(920)	(1,801)	(5,287)	(7,639)
Net interest and other expense	(93)	(354)	(455)	(911)
(Loss) income before income tax expense	(1,013)	(2,155)	(5,742)	(8,550)
Mobile Connectivity and Intertial Navigation Combined [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	3,363	2,416	7,482	5,994
Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	(4,283)	(4,217)	(12,769)	(13,633)
Operating Segments [Member] | Mobile Connectivity [Member]
Segment Reporting Information [Line Items]
Revenue, Net	33,425	32,762	99,938	101,083
Operating Income (Loss)	1,443	2,067	3,664	5,327
Operating Segments [Member] | Intertial Navigation [Member]
Segment Reporting Information [Line Items]
Revenue, Net	10,092	7,688	27,072	20,027
Operating Income (Loss)	$ 1,920	$ 349	$ 3,818	$ 667