Discontinued Operations - Disposal Groups, Including Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Discontinued Operations And Disposal Groups [Abstract]
Service revenue	$ 466	$ 427	$ 1,165	$ 902
Product sales	2,465	1,179	4,233	1,710
Total revenue	2,931	1,606	5,398	2,612
Cost of services, exclusive of depreciation expense shown below	345	309	690	874
Cost of product sales, exclusive of depreciation expense shown below	1,554	1,361	3,196	2,180
Depreciation and amortization		44		102
Other expense	117	14	91	22
Operating income (loss)	915	(122)	1,421	(566)
Gain on sale	8,804		8,804
Income (loss) from discontinued operations before income tax expense	9,719	(122)	10,225	(566)
Income tax expense (benefit)	1,748	206	1,995	108
Income (loss) from discontinued operations, net of income taxes	$ 7,971	$ (328)	$ 8,230	$ (674)
Current assets					$ 3,712
Non-current assets					1,848
Total assets					5,560
Current liabilities					1,633
Non-current liabilities					82
Total liabilities					$ 1,715