Revenue, Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Treatment Equipment [Abstract]
Lease term	36 months		36 months
Notice period to cancel contract agreement			60 days
Contract with Customer, Liability [Abstract]
Short-term contract liabilities	$ 211		$ 211
Long-term contract liabilities	162		162
Change in Contract with Customer, Liability [Abstract]
Contract liabilities recognized as revenue	55		130
Co-pay reimbursements recorded as reduction of revenue	$ (213)	$ (167)	$ (545)	$ (467)
South Korea [Member]
Treatment Equipment [Abstract]
Lease term	48 months		48 months