Summary of Significant Accounting Policies - Revenue Recognition - Condensed Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Summary of Significant Accounting Policies
Total revenue	$ 49,417	$ 35,936
Total cost of sales	24,083	14,451
Gross profit	25,334	21,485
Loss from operations	(17,321)	(20,208)
Net loss and comprehensive loss	$ (17,754)	$ (21,100)
Net loss per common share, basic and diluted	$ (1.08)	$ (1.69)
Product sales
Summary of Significant Accounting Policies
Total revenue	$ 39,514
Licensing, royalty and other revenue
Summary of Significant Accounting Policies
Total revenue	9,903
ASU 2014-09 | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Total revenue	45,925
Total cost of sales	23,329
Gross profit	22,596
Loss from operations	(20,059)
Net loss and comprehensive loss	$ (20,492)
Net loss per common share, basic and diluted	$ (1.25)
ASU 2014-09 | Adjustments
Summary of Significant Accounting Policies
Total revenue	$ (3,492)
Total cost of sales	(754)
Gross profit	(2,738)
Loss from operations	(2,738)
Net loss and comprehensive loss	$ (2,738)
Net loss per common share, basic and diluted	$ (0.17)
ASU 2014-09 | Product sales | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Total revenue	$ 36,599
ASU 2014-09 | Product sales | Adjustments
Summary of Significant Accounting Policies
Total revenue	(2,915)
ASU 2014-09 | Licensing, royalty and other revenue | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Total revenue	9,326
ASU 2014-09 | Licensing, royalty and other revenue | Adjustments
Summary of Significant Accounting Policies
Total revenue	$ (577)