Note 10 - Stock-based Compensation - RSU Activity (Details) - Restricted Stock Units (RSUs) [Member]	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Balance (in shares) | shares	81,019,401
Balance, weighted average issuance price (in dollars per share) | $ / shares	$ 0.13
Granted (in shares) | shares	0
Granted, weighted average issuance price (in dollars per share) | $ / shares	$ 0
Expired/Cancelled (in shares) | shares	(1,025,000)
Expired/Cancelled, weighted average issuance price (in dollars per share) | $ / shares	$ 0.04
Vested (in shares) | shares	(41,901)
Vested, weighted average issuance price (in dollars per share) | $ / shares	$ 0.17
Balance (in shares) | shares	79,952,500
Balance, weighted average issuance price (in dollars per share) | $ / shares	$ 0.04