Basis of Presentation (Tables)

6 Months Ended

Jun. 30, 2018

Basis of Presentation [Abstract]

Schedule of revenue disaggregated by revenue source

Revenue disaggregated by revenue source for the three and six months ended June 30, 2018 and 2017 consists of the following (in thousands). Revenue excludes sales and usage-based taxes where it has been determined that we are acting as a pass-through agent. 

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Product sales	$	1,376	$	1,629	$	2,220	$	3,069
Royalties		2,517		1,846		4,683		3,490
Total revenue	$	3,893	$	3,475	$	6,903	$	6,559