Revenue, Contract Liabilities (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Contract with Customer, Liability [Abstract]
Short-term contract liabilities	$ 82	$ 82
Long-term contract liabilities	231	231
Change in Contract with Customer, Liability [Abstract]
Contract liabilities recognized as revenue	$ 14	$ 35
Notice period to cancel contract agreement		60 days