Balance Sheet Accounts - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Royalties payable to commercial partners	$ 6,004	$ 7,139
Accrued research & development	1,686	1,245
Accrued professional fees	1,926	2,408
Accrued salary and other compensation	8,083	5,049
Accrued product costs	8,364	5,869
All other	2,298	1,809
Total Accrued expenses and other liabilities	$ 28,361	$ 23,519