Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Other Long-Term Liabilities
Net Deferred Tax Liabilities Related to IPR&P (Note 13)	$ 3,007	$ 3,007
Deferred Income From Sale of Tax Benefits	4,014	4,218
Other		1,083
Contingent Milestones (Note 3)	15,298	13,779
Deferred Revenue	754	1,586
Total	23,073	23,673
Less Current Portion	(2,777)	(4,526)
Long-Term Portion	$ 20,296	$ 19,147