Revenue (Tables)

9 Months Ended

Sep. 30, 2020

Revenue from Contract with Customer [Abstract]

Analysis of revenue by category

	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
	(in thousands)
Analysis of revenue by category
Licensing agreements	$	181	$	148	$	675	$	795
	$	181	$	148	$	675	$	795

Analysis of revenue by geography

	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
	(in thousands)
Analysis of revenue by geography:
United States	$	—	$	—	$	—	$	320
Latin America	181		148		675		475
	$	181	$	148	$	675	$	795