Note 8 - Stock-based Compensation (Details Textual) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Deferred Compensation Plan for Directors [Member]
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 0	$ 0
The 2014 Long-term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)	5,600,676
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	2,548,801
Share-based Payment Arrangement, Expense, Tax Benefit	$ 0	$ 0
The 2014 Long-term Incentive Plan [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 0
The 2014 Long-term Incentive Plan [Member] \| Share-based Payment Arrangement, Option [Member] \| Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
The 2014 Long-term Incentive Plan [Member] \| Share-based Payment Arrangement, Option [Member] \| Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
The 2014 Long-term Incentive Plan [Member] \| Share-based Payment Arrangement, Option [Member] \| Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
The 2014 Long-term Incentive Plan [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 80
Share-Based Compensation Arrangement By Share-based Payment Award, Performance Threshold, Operating Income	$ 1,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	354 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 75
The 2014 Long-term Incentive Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	2 years
The 2014 Long-term Incentive Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	4 years
The 2014 Long-term Incentive Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	33.33%
The 2014 Long-term Incentive Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	33.33%
The 2014 Long-term Incentive Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	33.33%

The threshold of operating income would trigger the vesting of share-based compensation awards.

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The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Number of shares authorized for issuance under share-based payment arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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