Summary of Significant Accounting Policies - Concentrations (Details) - item	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Total net revenue
Concentrations
Concentration risk (as a percentage)	89.00%	32.00%
Total net revenue | Customer 1
Concentrations
Concentration risk (as a percentage)	32.00%	11.00%
Total net revenue | Customer 2
Concentrations
Concentration risk (as a percentage)	31.00%	9.00%
Total net revenue | Customer 3
Concentrations
Concentration risk (as a percentage)	26.00%	12.00%
Total net revenue | Customer risk | Three major pharmaceutical distributors
Concentrations
Number of major distributors	3
Total net revenue | Customer risk | Three major pharmaceutical distributors | Minimum
Concentrations
Concentration risk (as a percentage)	10.00%
Total accounts receivable
Concentrations
Concentration risk (as a percentage)	86.00%	97.00%
Total accounts receivable | Customer 1
Concentrations
Concentration risk (as a percentage)	34.00%	34.00%
Total accounts receivable | Customer 2
Concentrations
Concentration risk (as a percentage)	31.00%	26.00%
Total accounts receivable | Customer 3
Concentrations
Concentration risk (as a percentage)	21.00%	37.00%