Note 10 - Common Stock and Stock-based Compensation Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands | Feb. 20, 2020 | Jul. 19, 2019 | May 07, 2019 | Feb. 19, 2019 | Jun. 30, 2020 | Dec. 31, 2019 |
Share-based Compensation Arrangement by Share-based Payment Award, Options and Stock Appreciation Rights, Outstanding Number (in shares) | [2] | | | | | 441,166 | [1] | 642,253 |
Share-based Compensation Arrangement by Share-based Payment Award, Options and Stock Appreciation Rights, Exercisable Number (in shares) | [2],[3] | | | | | 415,166 | | |
Projected Revenue Goal | | | | $ 41,000 | | | | |
Non-employee Director [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Annual Vesting, Percentage | | | | | | 25.00% | | |
Maximum [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | | | | | 4 years | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options and Stock Appreciation Rights, Outstanding Number (in shares) | | | | | | 422,500 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options and Stock Appreciation Rights, Exercisable Number (in shares) | | | | | | 396,500 | | |
Stock Appreciation Rights (SARs) [Member] | Maximum [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards Granted | | | | | | 400.00% | | |
Percentage of Stock Appreciation Rights Units Subject to Grant | | | | | | 75.00% | | |
The2011 Stock Incentive Plan [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options and Stock Appreciation Rights Vesting Percentage, Year One | | | | | | 25.00% | | |
Share-based Compensation Arrangement by Share-based Payment Award, Remaining Vesting Period (Month) | | | | | | 36 months | | |
Stock Options and SARs [Member] | | | | | | | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | | | | $ 4 | | |
Restricted Stock Units (RSUs) [Member] | Acquisition of Hillcrest Labs [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Remaining Vesting Period (Month) | | | 24 months | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | | 3 years | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | 52,000 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Employees Granted Shares (in shares) | | | 22 | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | | | $ 25.41 | | | | | |
Restricted Stock Units (RSUs) [Member] | Restricted Stock Units Vesting After One Year [Member] | Acquisition of Hillcrest Labs [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 34.00% | | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | | | 3 years | 3 years | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | | 10,000 | 30,000 | | | |
Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | Vesting on February 19, 2021 [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | 33.33% | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | Vesting on February 19, 2020 [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | 33.33% | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | Vesting on February 19, 2022 [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | 33.33% | | | | |
Performance Share Units [Member] | Chief Executive Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | | | 3 years | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares) | | | | 24,000 | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Number to Be Granted If 100% License Revenue Target is Met (in shares) | | | | 20,000 | | | | 23,200 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Percentage of License Revenue Target, Proportional Percentage to Be Received upon Achievement | | | | | | | | 116.00% |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Proportional Percentage to Be Received for Each Increase of 1 Percent Beyond the License Revenue Target | | | | 1.00% | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Ceiling as a Percentage of Baseline Number to Be Granted if the License Revenue Target is Exceeded | | | | 120.00% | | | | |
Performance Share Units [Member] | Key Employees [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | 3 years | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 18,500 | | | | | | |
Performance Share Units [Member] | Key Employees [Member] | PSUs Vesting After One Year [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | 24 months | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 34.00% | | | | | | |
Performance Share Units [Member] | Key Employees [Member] | Key Employees PSUs Goals One [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 50.00% | | | | | | |
Performance Share Units [Member] | Key Employees [Member] | Key Employees PSUs Goals Two [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 30.00% | | | | | | |
Performance Share Units [Member] | Key Employees [Member] | Key Employees PSUs Goals Three [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 20.00% | | | | | | |
Performance Share Units [Member] | Maximum [Member] | Chief Executive Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Percentage of License Revenue Target, Proportional Percentage to Be Received upon Achievement | | | | 99.00% | | | | |
Performance Share Units [Member] | Minimum [Member] | Chief Executive Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Percentage of License Revenue Target, Proportional Percentage to Be Received upon Achievement | | | | 90.00% | | | | |
Short-Term Executive PSUs [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Addtional Shares Issuable, Performance Goals Exceeded, Percentage | | 20.00% | | | | | | |
Short-Term Executive PSUs [Member] | Goals One [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 50.00% | | | | | | |
Short-Term Executive PSUs [Member] | Goals Two [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | 50.00% | | | | | | |
Short-Term Executive PSUs [Member] | Vesting on February 20, 2021 [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | 33.40% | | |
Short-Term Executive PSUs [Member] | Vesting on February 22, 2022 [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | 33.30% | | |
Short-Term Executive PSUs [Member] | Vesting on February 20, 2023 [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | | | | 33.30% | | |
Short-Term Executive PSUs [Member] | Chief Executive Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 17,045 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Addtional Shares Issuable, Performance Goals Exceeded (in shares) | | 3,410 | | | | | | |
Short-Term Executive PSUs [Member] | Executive Vice President, Worldwide Sales [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 5,113 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Addtional Shares Issuable, Performance Goals Exceeded (in shares) | | 1,023 | | | | | | |
Short-Term Executive PSUs [Member] | Chief Financial Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 4,545 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Addtional Shares Issuable, Performance Goals Exceeded (in shares) | | 909 | | | | | | |
Short-Term Executive PSUs [Member] | Chief Operating Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 4,545 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Addtional Shares Issuable, Performance Goals Exceeded (in shares) | | 909 | | | | | | |
Long-term PSUs [Member] | | | | | | | | |
Performance Goal, Minimum Market Cap for at Lease 30 Trading Days | | $ 1,000,000 | | | | | | |
Long-term PSUs [Member] | Chief Executive Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 56,818 | | | | | | |
Long-term PSUs [Member] | Executive Vice President, Worldwide Sales [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 35,511 | | | | | | |
Long-term PSUs [Member] | Chief Financial Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 28,409 | | | | | | |
Long-term PSUs [Member] | Chief Operating Officer [Member] | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | 28,409 | | | | | | |
RSUs and PSUs [Member] | | | | | | | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | | | | $ 17,713 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | | | | 409,437 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | | | | | | $ 27.65 | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) | | | | | | 1 year 6 months | | |
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[1] | Due to the ceiling imposed on the SAR grants, the outstanding amount equals a maximum of 422,500 shares of the Company's common stock issuable upon exercise. | |
[2] | The SAR units are convertible for a maximum number of shares of the Company’s common stock equal to 75% of the SAR units subject to the grant. | |
[3] | Due to the ceiling imposed on the SAR grants, the exercisable amount equals a maximum of 396,500 shares of the Company's common stock issuable upon exercise. | |