Segment Reporting - Depreciation and Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Depreciation	$ 8,810	$ 6,725	$ 7,608
Amortization expense	4,047	4,312	4,956
Unallocated, net
Segment Reporting Information [Line Items]
Depreciation	538	77	461
Amortization expense	0	0	0
Operating Segments
Segment Reporting Information [Line Items]
Depreciation	1,048	928	1,063
Amortization expense	0	0	0
Operating Segments | Mobile Connectivity
Segment Reporting Information [Line Items]
Depreciation	7,224	5,720	6,084
Amortization expense	$ 4,047	$ 4,312	$ 4,956