Accounts Receivable and Contract Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Accounts Receivable and Contract Assets [Abstract]
Accounts receivable - customers	$ 4,632	$ 4,731
Other receivables	186	385
Accounts receivable	4,818	5,116
Less: allowance for doubtful accounts	(343)	(305)
Accounts receivable, net	4,475	4,811
Unbilled revenue	2,274	$ 2,427
Change in accounts receivable - customers	(99)
Change in other receivables	(199)
Change in accounts receivable	(298)
Change in allowance for doubtful accounts	(38)
Change in accounts receivable, net	(336)
Change in unbilled revenue	$ (153)