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Note 2 - Investments - Current Investments (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Amortized cost | $ 33,778 | $ 29,166
Unrealized loss | (20) | (49)
Fair market value | 33,758 | 29,117
Corporate Bond Securities [Member] |  |
Amortized cost | 33,778 | 22,100
Unrealized loss | (20) | (46)
Fair market value | 33,758 | 22,054
Municipal Bonds [Member] |  |
Amortized cost |  | 3,727
Unrealized loss |  | (1)
Fair market value |  | 3,726
US Government Agencies Debt Securities [Member] |  |
Amortized cost |  | 3,339
Unrealized loss |  | (2)
Fair market value |  | $ 3,337

X
- Definition Amount before tax of current unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References No definition available. + Details
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X
- Definition This item represents the current cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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X
- Definition Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26626-111562 + Details
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- Details
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Data Type: | na
Balance Type: |
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X
- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
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