Revenue Recognition - Schedule of License, Royal and Other Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Revenue	$ 2,736	$ 2,529
Royalty Revenue [Member] \| Bellco License Agreement [Member]
Revenue	14	16
Other Revenue [Member]
Revenue	10	38
License Royalty and Other Revenue [Member]
Revenue	$ 24	$ 54

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details