Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue Recognition
Non-cash royalty revenue	$ 1,600	$ 1,500	$ 5,028	$ 4,300
Revenues \| Customer Concentration Risk \| Top Three Wholesale Pharmaceutical Distributors
Revenue Recognition
Concentration risk percentage (more than)	90.00%	90.00%	90.00%	90.00%
Accounts Receivable \| Customer Concentration Risk \| Top Three Wholesale Pharmaceutical Distributors
Revenue Recognition
Concentration risk percentage (more than)	90.00%	90.00%	90.00%	90.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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