Revenue - Schedule of Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Account receivables, net of allowance	$ 7,747	$ 7,735
Unbilled receivables - current	6,158	3,105
Deferred revenue	4,785	$ 6,595
Year-to-date Change [Member]
Account receivables, net of allowance	12
Unbilled receivables - current	3,053
Deferred revenue	$ (1,810)
Changes in Account receivables, net of allowance, percentage	0.20%
Changes in Unbilled receivables - current, percentage	98.30%
Changes in Deferred revenue, percentage	(27.40%)