Note 1 - Nature of Business, Financial Condition and Basis of Presentation (Tables)

9 Months Ended

Sep. 30, 2021

Notes Tables

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	September 30, 2021
	Gross Carrying Amount		Accumulated Amortization			Identifiable Intangible Assets, Net		Weighted-Average Useful Life (Years)
Finite-lived intangible assets:
Patents	$	4,496	$	(202	)	$	4,294		7.3
Defensive assets		4,804		—			4,804		8.4
Identifiable intangible assets	$	9,300	$	(202	)	$	9,098		7.9

	December 31, 2020
	Gross Carrying Amount		Accumulated Amortization			Identifiable Intangible Assets, Net		Weighted-Average Useful Life
Finite-lived intangible assets:
Patents	$	300	$	(186	)	$	114		5.2

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Year Ending December 31,	Patents		Defensive Assets		Total
2021 (remaining)	$	147	$	144	$	291
2022		601		575		1,176
2023		601		575		1,176
2024		601		575		1,176
2025		601		575		1,176
2026 and thereafter		1,743		2,360		4,103
Total	$	4,294	$	4,804	$	9,098

The 2021 Bonds [Member]

Notes Tables

Restrictions on Cash and Cash Equivalents [Table Text Block]

	September 30, 2021
Bond proceeds	$	68,995
Disbursement of funds		(20,005	)
Interest paid on bonds		(216	)
Interest income		10
Total restricted cash held by bond trustee	$	48,784