Balance Sheet Account Detail - Summary of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Key employee life insurance – cash surrender value	$ 6,274	$ 10,737
Inventories - non-current portion	1,876	3,100
Research & development supplies and other	1,340	231
Income tax receivable	668	668
Equity securities (see Note 11)	0
Equity securities (see Note 11)		37,530
CASI note - long term (see Note 11)	0	1,517
Other assets	$ 10,158	$ 53,783