Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2022

Revenue from Contract with Customer [Abstract]

Schedule of License, Royal and Other Revenue

	Three Months Ended March 31,
	2022		2021
	(in thousands)
Royalty revenue under the Bellco License Agreement	$	-	$	14
Other revenue		10		10
Total royalty and other revenue	$	10	$	24