Income Taxes - Valuation Allowance (Details) - Valuation Allowance, Deferred Tax Asset - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets Valuation Allowance [Roll Forward]
Balance at Beginning of Year	$ 1,238	$ 1,240
Charged to income tax (benefit) expense	311	(22)
Foreign currency	31	20
Increase due to Progenics acquisition	2,479
Release valuation allowance	(603)	0
Balance at End of Year	$ 3,456	$ 1,238