Note 11 - Stock Based Compensation and Other Plans (Details Textual) - USD ($) $ / shares in Thousands | Jan. 19, 2021 | Aug. 08, 2002 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 |
Share-based Payment Arrangement, Expense | | | $ 136,000 | $ 235,000 | |
The 2018 Plan [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | 585,000 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares) | | | 565,000 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares) | | | 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | | | $ 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | | | $ 3,000 | $ 0 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | | 320,000 | |
The 2018 Plan [Member] | Share-based Payment Arrangement, Option [Member] | | | | | |
Share-based Payment Arrangement, Expense | | | $ 34,000 | $ 90,000 | |
Share-based Payment Arrangement, Expense, Tax Benefit | | | 8,000 | $ 22,000 | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | $ 41,000 | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) | | | 2 years | | |
The 2018 Plan [Member] | Restricted Stock [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | 0 | 0 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares) | | | | | 10,000 |
Share-based Payment Arrangement, Expense | | | $ 0 | $ 4,000 | |
Share-based Payment Arrangement, Expense, Tax Benefit | | | 0 | 1,000 | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | $ 0 | 0 | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | | 4 years | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | | | $ 0 | 7,000 | |
The 2018 Plan [Member] | Restricted Stock [Member] | Share-based Compensation, Annual [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 25.00% | | |
The 2008 Plan [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | 3,044,927 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | | | $ 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | | | $ 6,000 | 257,000 | |
Share-based Payment Arrangement, Expense | | | 95,000 | 139,000 | |
Share-based Payment Arrangement, Expense, Tax Benefit | | | 24,000 | $ 35,000 | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | $ 17,000 | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) | | | 1 year | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | | | |
The 2008 Plan [Member] | Restricted Stock [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | | | 0 | 0 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance (in shares) | | | | | 1,000 |
Share-based Payment Arrangement, Expense | | | $ 0 | $ 1,200 | |
Share-based Payment Arrangement, Expense, Tax Benefit | | | 0 | 0 | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | $ 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | | | 4 years | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | | | $ 0 | $ 1,000 | |
The 2008 Plan [Member] | Restricted Stock [Member] | Share-based Compensation, Annual [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | | | 25.00% | | |
The 2020 Plan [Member] | Subsequent Event [Member] | The 19 Employees [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 125,000 | | | | |
The 2020 Plan [Member] | Subsequent Event [Member] | Director One [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 10,000 | | | | |
The 2020 Plan [Member] | Subsequent Event [Member] | Each Member of Board of Directors [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 50,000 | | | | |
The 2020 Plan [Member] | Subsequent Event [Member] | Director Two [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 10,000 | | | | |
The 2020 Plan [Member] | Subsequent Event [Member] | Director Three [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 10,000 | | | | |
The 2020 Plan [Member] | Subsequent Event [Member] | Director Four [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 10,000 | | | | |
The 2020 Plan [Member] | SGRP Shares [Member] | Subsequent Event [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares) | 600,000 | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) | 550,000 | | | | |
The 2020 Plan [Member] | SGRP Shares for Each of Up to First Three Additional New Directors During Period December 1, 2020, to April 30, 2021 [Member] | Subsequent Event [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) | 50,000 | | | | |
The 2020 Plan [Member] | SGRP Shares for Three Additional New Directors During Period December 1, 2020, to April 30, 2021 [Member] | Subsequent Event [Member] | Maximum [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) | 700,000 | | | | |
The 2020 Plan [Member] | Share-based Payment Arrangement, Option [Member] | Subsequent Event [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares) | 35,000 | | | | |
Inducement Plan [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | | | $ 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | | | $ 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) | | | 200,000 | 200,000 | |
Inducement Plan [Member] | Share-based Payment Arrangement, Option [Member] | | | | | |
Share-based Payment Arrangement, Expense | | | $ 7,000 | $ 0 | |
Share-based Payment Arrangement, Expense, Tax Benefit | | | 2,000 | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | | | $ 71,000 | | |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) | | | 4 years | | |
ESP Plan [Member] | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award Purchase Price of Common Stock Discount Rate | | 15.00% | | | |
CSP Plan [Member] | | | | | |
Affiliate Purchase Price of Common Stock Percent | | 15.00% | | | |