Revenue Recognition, Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Treatment Equipment [Abstract]
Lease term	36 months		36 months
Contract with Customer, Liability [Abstract]
Short-term contract liabilities	$ 139		$ 139
Long-term contract liabilities	23		23
Change in Contract with Customer, Liability [Abstract]
Contract liabilities recognized as revenue	52		162
Co-pay reimbursements recorded as reduction of revenue	$ (160)	$ (213)	$ (414)	$ (545)
Minimum [Member]
Treatment Equipment [Abstract]
Notice period to cancel contract agreement			30 days
Maximum [Member]
Treatment Equipment [Abstract]
Notice period to cancel contract agreement			60 days
South Korea [Member]
Treatment Equipment [Abstract]
Lease term	48 months		48 months