Summary of Significant Accounting Policies - Revenue Recognition - Condensed Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Summary of Significant Accounting Policies
Total revenue	$ 10,765		$ 25,618
Total cost of sales	5,459		10,357
Gross profit	5,306	$ 5,792	15,261	$ 10,009
Loss from operations	(6,509)	(4,789)	(7,619)	(10,664)
Net loss and comprehensive loss	$ (6,599)	$ (5,187)	$ (7,876)	$ (11,273)
Net loss per common share, basic and diluted	$ (0.40)	$ (0.42)	$ (0.50)	$ (0.91)
Product sales
Summary of Significant Accounting Policies
Total revenue	$ 9,449		$ 18,814
Licensing, royalty and other revenue
Summary of Significant Accounting Policies
Total revenue	1,316		6,804
ASU 2014-09 | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Total revenue	10,053		24,103
Total cost of sales	5,566		10,170
Gross profit	4,487		13,933
Loss from operations	(7,328)		(8,947)
Net loss and comprehensive loss	$ (7,418)		$ (9,204)
Net loss per common share, basic and diluted	$ (0.45)		$ (0.58)
ASU 2014-09 | Adjustments
Summary of Significant Accounting Policies
Total revenue	$ (712)		$ (1,515)
Total cost of sales	107		(187)
Gross profit	(819)		(1,328)
Loss from operations	(819)		(1,328)
Net loss and comprehensive loss	$ (819)		$ (1,328)
Net loss per common share, basic and diluted	$ (0.05)		$ (0.08)
ASU 2014-09 | Product sales | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Total revenue	$ 8,863		$ 17,396
ASU 2014-09 | Product sales | Adjustments
Summary of Significant Accounting Policies
Total revenue	(586)		(1,418)
ASU 2014-09 | Licensing, royalty and other revenue | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Total revenue	1,190		6,707
ASU 2014-09 | Licensing, royalty and other revenue | Adjustments
Summary of Significant Accounting Policies
Total revenue	$ (126)		$ (97)