Segment Information - Summary of Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Summary of Company's capital expenditures by segment
Capital expenditures	$ 839	$ 17,675
Operating Segments | Radiology
Summary of Company's capital expenditures by segment
Capital expenditures	812	16,926
Operating Segments | Oncology
Summary of Company's capital expenditures by segment
Capital expenditures	12	484
Operating Segments | Interventional
Summary of Company's capital expenditures by segment
Capital expenditures	15	33
Corporate / Other
Summary of Company's capital expenditures by segment
Capital expenditures	$ 0	$ 232