Segment Reporting - Net Sales and Operating Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net sales									$ 157,893	$ 153,029
Operating income (loss)	$ (3,325)	$ (4,858)	$ (6,679)	$ (6,234)	$ (2,377)	$ (1,857)	$ (2,580)	$ (3,832)	(21,096)	(10,646)
Net interest and other income (expense)									1,084	(452)
Loss from continuing operations before income tax (benefit) expense									(20,012)	(11,098)
Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)									(2,608)	5,598
Operating Segments | Mobile Connectivity
Segment Reporting Information [Line Items]
Net sales									122,015	115,926
Operating income (loss)									(5,569)	681
Operating Segments | Intertial Navigation
Segment Reporting Information [Line Items]
Net sales									35,878	37,103
Operating income (loss)									2,961	4,917
Unallocated, net
Segment Reporting Information [Line Items]
Operating income (loss)									$ (18,488)	$ (16,244)