Note 7 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 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
Restricted stock unit awards granted		(100	)		-			-
Stock option awards granted		(1,074	)		1,074			10.06
Stock option awards exercised		-			(586	)		3.97
Stock option awards cancelled		39			(39	)		8.15
Balance March 31, 2021		3,457			25,334		$	6.72

							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		-			(7	)		3.63
Stock option awards cancelled		27			(27	)		2.44
Balance March 31, 2021		118			4,275		$	4.04

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	%		83.5	%
Expected Dividend Yield	0.0	%		0.0	%
Risk-Free Interest Rate	0.8	%		0.8	%