Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Schedule of License, Royal and Other Revenue

Royalty and other revenues recognized for the three months ended March 31, 2021 and 2020 is comprised of:

	Three Months Ended March 31,
	2021		2020
	(in thousands)
Royalty revenue under the Bellco License Agreement	$	14	$	16
Other revenue		10		38
Total royalty and other revenue	$	24	$	54