Note 9 - Stockholders' Equity (Details Textual) | May 26, 2020USD ($)$ / sharesshares | Apr. 23, 2016 | Aug. 31, 2019$ / sharesshares | Mar. 31, 2021shares | Dec. 31, 2021USD ($)$ / sharesshares | Dec. 31, 2020USD ($)$ / sharesshares | Oct. 01, 2018$ / shares | Sep. 06, 2017USD ($) | Jun. 22, 2017$ / sharesshares | Sep. 17, 2014USD ($) | Jun. 07, 2012USD ($) |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares) | | | | | 1,600,000 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price, Ending Balance (in dollars per share) | $ / shares | | | | | $ 1.96 | $ 1.27 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | | | 957,000 | | | | | | |
Share-based Payment Arrangement, Expense | $ | | | | | $ 1,854,000 | $ 1,984,000 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares) | | | | | 4,381,348 | 3,758,670 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year) | | | | | 4 years 3 months 18 days | 4 years 8 months 12 days | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares) | | | | | 100,278 | 22,373 | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares | | | | | $ 2.27 | $ 3.35 | | | | | |
Minimum Percentage of Outstanding Common Stock Acquired | 4.90% | | | | | | | | | | |
Stock Repurchase Program, Authorized Amount | $ | | | | | | | | $ 3,000,000 | | $ 1,000,000 | $ 2,000,000 |
Stock Repurchased During Period, Shares (in shares) | | | | | 0 | 0 | | | | | |
Stock Repurchase Program, Remaining Authorized Repurchase Amount | $ | | | | | $ 2,300,000 | | | | | | |
Measurement Input, Risk Free Interest Rate [Member] | | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | 0.019 | | | | | | | | | | |
Measurement Input, Price Volatility [Member] | | | | | | | | | | | |
Warrants and Rights Outstanding, Measurement Input | 0.74 | | | | | | | | | | |
AWI Warrant [Member] | | | | | | | | | | | |
Warrants and Rights Outstanding, Term (Year) | 7 years | | | | | | | | | | |
AWI Warrants First One-third [Member] | | | | | | | | | | | |
Minimum Price of Common Stock Weighted Average Closing Price (in dollars per share) | $ / shares | | | | | | | $ 30 | | | | |
AWI Warrants Second One-third [Member] | | | | | | | | | | | |
Minimum Price of Common Stock Weighted Average Closing Price (in dollars per share) | $ / shares | | | | | | | 37.50 | | | | |
AWI Warrants Last One-third [Member] | | | | | | | | | | | |
Minimum Price of Common Stock Weighted Average Closing Price (in dollars per share) | $ / shares | | | | | | | $ 45 | | | | |
AWI [Member] | | | | | | | | | | | |
Equity Method Investment, Ownership Percentage | 15.00% | | | | | | | | | | |
Series A Junior Participating Preferred Stock [Member] | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | $ 20 | | | | | | | | | | |
Series B Preferred Stock [Member] | AWI Warrant [Member] | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | $ 1.72 | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | 148,240 | | | | | | | | | | |
Warrants and Rights Outstanding | $ | $ 2,500,000 | | | | | | | | | | |
Common Stock [Member] | AWI Warrant [Member] | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares | | | | | | | | | $ 18.45 | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | | | | | | | | | 1,482,400 | | |
Service-based Option [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price, Ending Balance (in dollars per share) | $ / shares | | | | | $ 1.96 | $ 1.27 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | | | 957,000 | 635,000 | | | | | |
Share-based Payment Arrangement, Expense | $ | | | | | $ 1,417,000 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares) | | | | | 4,031,348 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year) | | | | | 7 months 6 days | | | | | | |
Service-based Option [Member] | Share-based Payment Arrangement, Employee [Member] | Share-based Payment Arrangement, Tranche One [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | 33.33% | | | | | | |
Service-based Option [Member] | Share-based Payment Arrangement, Employee [Member] | Share-based Payment Arrangement, Tranche Two [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | 33.33% | | | | | | |
Service-based Option [Member] | Share-based Payment Arrangement, Employee [Member] | Share-based Payment Arrangement, Tranche Three [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | 33.33% | | | | | | |
Service-based Option [Member] | Minimum [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) | | | | | 7 years | | | | | | |
Service-based Option [Member] | Maximum [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) | | | | | 10 years | | | | | | |
Market Condition Option [Member] | Officer [Member] | Equity Incentive Plan 2018 [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) | | | | | 7 years | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | 455,000 | | | | | | | | |
Share-based Payment Arrangement, Expense | $ | | | | | $ 111,000 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares) | | | | | 355,000 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year) | | | | | 7 months 6 days | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares | | | $ 1.69 | | | | | | | | |
Service-based Restricted Stock Awards [Member] | | | | | | | | | | | |
Share-based Payment Arrangement, Expense | $ | | | | | $ 351,074 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares) | | | | | 185,082 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms (Year) | | | | | 2 years 2 months 12 days | | | | | | |
Service-based Restricted Stock Awards [Member] | Share-based Payment Arrangement, Employee [Member] | Executive Officer [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted (in shares) | | | | 220,000 | | | | | | | |
Service-based Restricted Stock Awards [Member] | Share-based Payment Arrangement, Employee [Member] | Executive Officer [Member] | First Anniversary of the Date of Award [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Forfeiture Restriction, Percentage | | 33.33% | | | | | | | | | |
Service-based Restricted Stock Awards [Member] | Share-based Payment Arrangement, Employee [Member] | Executive Officer [Member] | Second Anniversary of the Date of Award [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Forfeiture Restriction, Percentage | | 33.33% | | | | | | | | | |
Service-based Restricted Stock Awards [Member] | Share-based Payment Arrangement, Employee [Member] | Executive Officer [Member] | Third Anniversary of the Date of Award [Member] | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Forfeiture Restriction, Percentage | | 33.33% | | | | | | | | | |