Customer, Supplier and Product Concentration - Additional Information (Details) - customer	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Risks and Uncertainties [Abstract]
Number of customers considered as concentration risks	3	3
Prescription Pharmaceuticals \| Net Revenue \| Segment Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	89.20%	89.30%
Myorisan \| Net Revenue \| Product Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	12.00%

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