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Note 11 - Retirement Plans (Details Textual) | 12 Months Ended
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Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Company Matching Percentage on First Six Percent of Employee Contributions | 50.00% |  |
Employee Contribution Percentage for Which Company Will Match at Fifty Percent | 6.00% |  |
Defined Contribution Plan Number of Investment Options | 24 |  |
Number of Non-contributory Defined Benefit Plans | 2 |  |
Pension and Other Postretirement Defined Benefit Plans, Liabilities | $ 1,900,000 | $ 1,900,000 |
Accumulated Other Comprehensive Income Loss Unrecognized Net Actuarial Losses Net of Tax | 1,500,000 | 1,600,000 |
Defined Benefit Plan, Accumulated Benefit Obligation | 6,500,000 | 6,400,000 |
Defined Benefit Plan, Fair Value of Plan Assets | 4,600,000 | 4,500,000 |
Defined Benefit Plan, Net Periodic Benefit Cost | $ 400,000 | $ 400,000 | $ 200,000
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | 3.74% | 3.91% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets | 7.50% | 7.50% |
Company Matching Percentage on First Ten Thousand Dollar Employee Contributions | 50.00% |  |
Officer Contribution for Which Company Will Match at Fifty Percent | $ 10,000 |  |
Select Employee Contribution for Which Company Will Match at Fifty Percent | $ 5,000 |  |
Retirement Target Benefit Plan, Percentage of Final Base Pay after 35-year Career | 35.00% |  |
Retirement Target Benefit Plan, Percentage of Final Base Pay per Year of Service | 1.00% |  |
Non-qualified Retirement Savings Plan Actuarial Yearly Asset Growth Percentage Assumption | 8.00% |  |
Deferred Compensation Liability, Current and Noncurrent | $ 6,200,000 | $ 6,400,000 |
Retirement Plan Expense | $ 1,400,000 | $ 1,500,000 | $ 1,800,000

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- Definition For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accumulated Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6503844 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition The interest rate used to adjust for the time value of money for the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Expected Long-Term Rate of Return on Plan Assets -URI http://asc.fasb.org/extlink&oid=6512046 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Definition The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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