Note 7 - Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

Notes Tables

Share-based Payment Arrangement, Activity [Table Text Block]

							Weighted
							Average
	Awards			Options			Exercise
	Available			Outstanding			Price
Balance December 31, 2020		4,592			24,885		$	6.52
Plan amendment		7,500			-			-
Restricted stock unit awards granted		(100	)		-			-
Stock option awards granted		(1,928	)		1,928			11.47
Stock option awards exercised		-			(1,619	)		4.23
Stock option awards cancelled		105			(105	)		7.59
Balance June 30, 2021		10,169			25,089		$	7.04

							Weighted
							Average
	Awards			Options			Exercise
	Available			Outstanding			Price
Balance December 31, 2020		229			4,171		$	3.88
Stock option awards granted		(138	)		138			8.52
Stock option awards exercised		—			(30	)		2.54
Stock option awards cancelled		78			(78	)		3.57
Balance June 30, 2021		169			4,201		$	4.05

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2021		2020
Expected Life in Years	5.5			5.5
Expected Volatility	84.2	%		83.7	%
Expected Dividend Yield	0.0	%		0.0	%
Risk-Free Interest Rate	0.8	%		0.5	%