Note 11 - Equity Incentive Plans - Summary of Stock Option Transactions (Details) - $ / shares		9 Months Ended
	Mar. 24, 2020	Sep. 30, 2020	Sep. 30, 2019
Shares available for grant, balance (in shares)		295,180
Number of options outstanding, beginning balance (in shares)		1,811,652
Weighted average exercise price, balance (in dollars per share)		$ 2.74
Shares availabe for grant, 2019 Plan Amendment (in shares)		6,400,000
Shares available for grant, granted (in shares)		(4,957,800)
Number of options outstanding, granted (in shares)		4,957,800
Weighted average exercise price, granted (in dollars per share)	$ 1.70	$ 2.10
Number of options outstanding, exercised (in shares)		(305,179)	0
Weighted average exercise price, exercised (in dollars per share)		$ 1.32
Shares available for grant, forfeited (in shares)		85,910
Number of options outstanding, forfeited (in shares)		(85,992)
Weighted average exercise price, forfeited (in dollars per share)		$ 0.39
Shares available for grant, canceled (in shares)		9,573
Number of options outstanding, canceled (in shares)		(57,751)
Weighted average exercise price, canceled (in dollars per share)		$ 10.57
Shares available for grant, balance (in shares)		1,554,328
Number of options outstanding, balance (in shares)		6,320,530
Weighted average exercise price, balance (in dollars per share)		$ 2.27
Performance-based Restricted Stock Units (PRSUs) [Member]
Shares available for grant, PRSU's granted (in shares)		(278,535)