v3.8.0.1

Note 2 - Investments and Fair Value Measurement - Summary of Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Amortized Cost | $ 60,469 | $ 80,307
Gross Unrealized Gains |  | 3
Gross Unrealized Losses |  |
Fair Value | 60,469 | 80,310
Cash and cash equivalents: |  |
Amortized Cost | 60,469 | 80,307
Gross Unrealized Gains |  | 3
Gross Unrealized Losses |  |
Fair Value | 60,469 | 80,310
Cash and Cash Equivalents [Member] |  |
Amortized Cost | 52,902 | 80,307
Gross Unrealized Gains |  | 3
Gross Unrealized Losses |  |
Fair Value | 52,902 | 80,310
Cash and cash equivalents: |  |
Amortized Cost | 52,902 | 80,307
Gross Unrealized Gains |  | 3
Gross Unrealized Losses |  |
Fair Value | 52,902 | 80,310
Cash and Cash Equivalents [Member] | Cash [Member] |  |
Amortized Cost | 29,765 | 49,833
Gross Unrealized Gains |  |
Gross Unrealized Losses |  |
Fair Value | 29,765 | 49,833
Cash and cash equivalents: |  |
Amortized Cost | 29,765 | 49,833
Gross Unrealized Gains |  |
Gross Unrealized Losses |  |
Fair Value | 29,765 | 49,833
Cash and Cash Equivalents [Member] | U.S. Government Agency Securities [Member] |  |
Amortized Cost | 23,137 | 30,474
Gross Unrealized Gains |  | 3
Gross Unrealized Losses |  |
Fair Value | 23,137 | 30,477
Cash and cash equivalents: |  |
Amortized Cost | 23,137 | 30,474
Gross Unrealized Gains |  | 3
Gross Unrealized Losses |  |
Fair Value | 23,137 | $ 30,477
Marketable Securities [Member] |  |
Amortized Cost | 7,567 |
Gross Unrealized Gains |  |
Gross Unrealized Losses |  |
Fair Value | 7,567 |
Cash and cash equivalents: |  |
Amortized Cost | 7,567 |
Gross Unrealized Gains |  |
Gross Unrealized Losses |  |
Fair Value | 7,567 |
Marketable Securities [Member] | U.S. Government Agency Securities [Member] |  |
Amortized Cost | 7,567 |
Gross Unrealized Gains |  |
Gross Unrealized Losses |  |
Fair Value | 7,567 |
Cash and cash equivalents: |  |
Amortized Cost | 7,567 |
Gross Unrealized Gains |  |
Gross Unrealized Losses |  |
Fair Value | $ 7,567 |

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + 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 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
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- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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