Property and Equipment (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 43,003	$ 46,694
Outside of the United States
Property, Plant and Equipment [Line Items]
Property and equipment, net	2,961
Gamma Knife
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 729
Medical Equipment and Facilities | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Medical Equipment and Facilities | Maximum
Property, Plant and Equipment [Line Items]
Useful life	10 years
PBRT Equipment
Property, Plant and Equipment [Line Items]
Useful life	20 years