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Note 8 - Line of Credit and Long-term Debt (Details Textual) $ in Thousands |  | 12 Months Ended |
--- | --- | --- | ---
Oct. 25, 2018 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Mar. 31, 2020 USD ($)
Interest Expense, Debt and Finance Leases, Net of Amounts Capitalized |  | $ 900 | $ 500 | $ 600 |
Interest Costs Capitalized |  | 100 |  |  |
Letters of Credit Outstanding, Amount |  | $ 1,600 |  |  |
Wells Fargo Bank, N.A. [Member] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity | $ 74,000 |  |  |  |
Maximum Senior Leverage Ratio |  | 3.00 |  |  |
Minimum Fixed Charge Coverage Ratio |  | 1.10 |  |  |
Letters of Credit Outstanding, Amount |  | $ 1,600 |  |  |
Wells Fargo Bank, N.A. [Member] | Term Loan [Member] |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  | $ 15,900
Long-term Debt, Monthly Repayment of Principal |  | 300 |  |  |
Long-term Debt, Total |  | $ 13,800 |  |  |
Debt Instrument, Covenant, Maximum Debt Percentage of Securing Property |  | 60.00% |  |  |
Debt Instrument, Covenant, Repayment Percentage of Excess Cash Flow |  | 20.00% |  |  |
Debt Instrument, Prepayment from Excess Cash Flow Generated, Amount Payable in Next 12 Months |  | $ 4,600 |  |  |
Wells Fargo Bank, N.A. [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Term Loan [Member] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 2.00% |  |  |
Wells Fargo Bank, N.A. [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Term Loan [Member] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 2.50% |  |  |
Wells Fargo Bank, N.A. [Member] | Revolving Credit Facility [Member] |  |  |  |  |
Long-term Line of Credit, Total |  | $ 0 | $ 0 |  |
Line of Credit Facility, Remaining Borrowing Capacity |  | $ 53,000 |  |  |
Debt, Weighted Average Interest Rate |  | 1.73% | 3.43% |  |
Wells Fargo Bank, N.A. [Member] | Revolving Credit Facility [Member] | Minimum [Member] |  |  |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.25% |  |  |  |
Wells Fargo Bank, N.A. [Member] | Revolving Credit Facility [Member] | Maximum [Member] |  |  |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.375% |  |  |  |
Wells Fargo Bank, N.A. [Member] | Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 1.50% |  |  |  |
Wells Fargo Bank, N.A. [Member] | Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 2.00% |  |  |  |

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- Definition The percentage of excess cash flow that repayment may be required under debt instrument covenant + References No definition available. + Details
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- Definition Represents the amount required during the next 12 months for prepayment from excess cash flow generated during the current fiscal year. + References No definition available. + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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