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Note 14 - Debt (Details Textual) - USD ($) $ in Thousands |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Apr. 06, 2021 | Nov. 01, 2020 | Sep. 16, 2020 | May 31, 2020 | Sep. 30, 2020 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Feb. 03, 2022
Property, Plant and Equipment, Net, Ending Balance |  |  |  |  |  | $ 54,871,000 | $ 54,161,000 |  |
Debt Conversion, Converted Instrument, Amount |  |  |  |  |  | 100,000 | 250,000 | $ 250,000 |
Proceeds from Issuance of Commercial Paper |  |  |  |  |  | 2,100,000 |  |  |
Repayments of Commercial Paper |  |  |  |  |  | $ 1,800,000 |  |  |
Commercial Paper, Maturity Duration, Minimum (Day) |  |  |  |  |  | 7 days |  |  |
Commercial Paper Maturity Duration, Maximum (Day) |  |  |  |  |  | 86 days |  |  |
Commercial Paper |  |  |  |  |  | $ 400,000 | 75,000 |  |
Board of Directors Authorized Debt Issuance |  |  |  |  |  |  |  | 6,000,000 |
Previous Board of Directors Remaining Debt Issuance |  |  |  |  |  |  |  | $ 2,250,000 |
Board of Directors Remaining Debt Issuance |  |  |  |  |  | 2,500,000 |  |  |
Long-term Debt, Gross |  |  |  |  |  | 31,492,000 |  |  |
Secured Debt [Member] |  |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  |  |  | 300,000 | 0 |  |
Subsequent Event [Member] |  |  |  |  |  |  |  |  |
Board of Directors Authorized Debt Issuance |  |  |  |  |  |  |  |  | $ 12,000,000
Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |
Line of Credit Facility, Remaining Borrowing Capacity |  |  |  |  |  | 2,000,000 |  |  |
Long-term Line of Credit, Total |  |  |  |  |  | $ 0 |  |  |
Debt Instrument, Term (Year) |  |  |  |  |  | 5 years |  |  |
Allowable Debt Per Debt to Net Worth Coverage Ratio as Defined Facility |  |  |  |  |  | $ 41,200,000 |  |  |
Outstanding Debt as Defined by Facility |  |  |  |  |  | 31,500,000 |  |  |
CrossDefaultProvisionAsDefinedByFacility |  |  |  |  |  | 150,000 |  |  |
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |  |  |  |  |
Line of Credit Facility, Remaining Borrowing Capacity |  |  |  |  |  | 2,000,000 |  |  |
Three Bilateral Revolving Credit Facilities [Member] |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  | $ 600,000 |  |  |  |  |
Line of Credit Facility, Maximum Amount Outstanding During Period |  |  |  | 300,000 |  |  |  |  |
Repayments of Lines of Credit |  |  |  | $ 300,000 |  |  |  |  |
Line of Credit Facility, Expiration Date |  |  |  | May 18, 2021 |  |  |  |  |
Conversion of Existing Notes [Member] |  |  |  |  |  |  |  |  |
Debt Conversion, Original Debt, Amount | $ 1,700,000 |  |  |  |  |  |  |  |
Payment of Financing and Stock Issuance Costs, Total | 257,000 |  |  |  |  |  |  |  |
Gain (Loss) on Extinguishment of Debt, Total | $ 0 |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Issuance Date | Apr. 06, 2021 |  |  |  |  |  |  |  |
Conversion of Existing Notes [Member] | Interest Expense [Member] |  |  |  |  |  |  |  |  |
Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction | $ 13,000 |  |  |  |  |  |  |  |
Conversion of Existing Notes into New 2036 Notes [Member] |  |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Amount | $ 701,000 |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Rate | 2.891% |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Expiration or Due Date | Apr. 06, 2036 |  |  |  |  |  |  |  |
Conversion of Existing Notes into New 2071 Notes [Member] |  |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Amount | $ 1,000,000 |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Rate | 3.799% |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Expiration or Due Date | Apr. 06, 2071 |  |  |  |  |  |  |  |
Conversion of Existing Notes for New 2.973% Notes, Due September 16, 2062 [Member] |  |  |  |  |  |  |  |  |
Debt Conversion, Original Debt, Amount |  |  | $ 1,047,000 |  |  |  |  |  |
Debt Conversion, Converted Instrument, Amount |  |  | $ 1,047,000 |  |  |  |  |  |
Debt Conversion, Converted Instrument, Rate |  |  | 2.973% |  |  |  |  |  |
Debt Conversion, Converted Instrument, Issuance Date |  |  | Sep. 16, 2020 |  |  |  |  |  |
Debt Conversion, Converted Instrument, Expiration or Due Date |  |  | Sep. 16, 2062 |  |  |  |  |  |
Conversion of Existing Notes for New 2.973% Notes, Due September 16, 2062 [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |
Debt Conversion, Original Debt, Due Date of Debt |  |  | May 01, 2037 |  |  |  |  |  |
Conversion of Existing Notes for New 2.973% Notes, Due September 16, 2062 [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Debt Conversion, Original Debt, Due Date of Debt |  |  | Mar. 01, 2049 |  |  |  |  |  |
Conversion of Existing Notes for New 2.973% Notes, Due September 16, 2062 [Member] | Interest Expense [Member] |  |  |  |  |  |  |  |  |
Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction |  |  |  |  | $ 9,000 |  |  |  |
4.0% Notes, Due February 1, 2021 [Member] |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  | $ 500,000 |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 4.00% |  |  |  |  |  |  |
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed |  | 100.00% |  |  |  |  |  |  |
Debt Instrument, Repurchase Date |  | Nov. 01, 2020 |  |  |  |  |  |  |
Existing Notes [Member] |  |  |  |  |  |  |  |  |
Interest Paid, Including Capitalized Interest, Operating and Investing Activities, Total | $ 14,000 |  |  |  |  |  |  |  |
Conversion of Existing Notes for New 2.973% Notes, Due September 16, 2062 [Member] |  |  |  |  |  |  |  |  |
Payment of Financing and Stock Issuance Costs, Total |  |  | $ 319,000 |  |  |  |  |  |
Interest Paid, Including Capitalized Interest, Operating and Investing Activities, Total |  |  | 4,000 |  |  |  |  |  |
Gain (Loss) on Extinguishment of Debt, Total |  |  | $ 0 |  |  |  |  |  |
Equipment [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment, Net, Ending Balance |  |  |  |  |  | 7,747,000 | 7,905,000 |  |
Asset Pledged as Collateral [Member] | Equipment [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment, Net, Ending Balance |  |  |  |  |  | $ 1,200,000 | $ 1,300,000 |  |

X
- Definition Total amount of debt (as defined in the facility) the debt-to-net-worth coverage ratio allowable under the revolving credit facility. + References No definition available. + Details
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- Definition Maximum duration of commercial paper maturities, in 'PnYnMnDTnHnMnS' format, for example, P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition The value of the financial instrument(s) that the original debt is being converted into in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586 + Details
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- Definition Expiration, mandatory redemption, or due date, in YYYY-MM-DD format, of the financial instrument issued in exchange for the original debt being converted in a noncash or part noncash transaction. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586 + Details
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- Definition Dividend or interest rate associated with the financial instrument issued in exchange for the original debt being converted in a noncash or part noncash transaction. Noncash are transactions that affect recognized assets or liabilities but that do not result in cash receipts or cash payments. Part noncash refers to that portion of the transaction not resulting in cash receipts or cash payments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586 + Details
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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 Reference 2: 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 Reference 3: 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 4: 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 + Details
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