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Note 7 - Share-Based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Aug. 31, 2013 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Allocated Share-based Compensation Expense |  | $ 8,487 | $ 9,705 | $ 10,177 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross |  | 2,248,000 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value |  | $ 2.17 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized |  | $ 14,541 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Expected to be Recognized Next Year |  | 6,880 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Expected to be Recognized Year Two |  | 4,649 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Expected to be Recognized Year Three |  | 2,606 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Expected to be Recognized Year Four |  | $ 406 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant |  | 2,273,000 | 16,000 | 2,362,000 | 1,082,000
Incentive Plan [Member] |  |  |  |  |
Allocated Share-based Compensation Expense |  | $ 8,340 | $ 9,485 | $ 9,963 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term |  | 6 years 219 days |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value |  | $ 2.17 | $ 7.72 | $ 8.02 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value |  | $ 339 | $ 10,117 | $ 8,522 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value |  | 20,002 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value |  | $ 6,380 | 4,492 | $ 2,844 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number |  | 11,013 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price |  | $ 6.53 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term |  | 6 years 182 days |  |  |
Incentive Plan [Member] | Employee Stock Option [Member] | Minimum [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term |  | 5 years |  |  |
Incentive Plan [Member] | Employee Stock Option [Member] | Maximum [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term |  | 10 years |  |  |
Incentive Plan [Member] | Employee Stock Option [Member] | Non-employee Directors [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, First Vesting Period After Grant Date |  | 1 year |  |  |
Incentive Plan [Member] | Employee Stock Option [Member] | Vest 25% Each Year Until Fully Vested [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 25.00% |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 4 years |  |  |
Incentive Plan [Member] | Stock Options and Restricted Stock [Member] | Vest 50% Each Year Until Fully Vested [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 50.00% |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 2 years |  |  |
Incentive Plan [Member] | Performance Shares [Member] | Vest Upon Successful Completion of Specific Development Milestones [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | 1,032,000 |  |  | 1,250,000 |
Incentive Plan [Member] | Performance Shares [Member] | Vest Upon Successful Completion of Specific Development Milestones [Member] | August 2013 [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 75.00% |  |  |
Share-based Compensation Arrangement by Shar-based Payment Award, Awards Unvested, Percentage |  | 25.00% |  |  |
Incentive Plan [Member] | Performance Shares [Member] | Vest Upon Successful Completion of Specific Development Milestones [Member] | December 2014 [Member] |  |  |  |  |
Share-based Compensation Arrangement by Shar-based Payment Award, Awards Unvested, Percentage |  | 100.00% |  |  |
Employee Stock Purchase Plan [Member] |  |  |  |  |
Allocated Share-based Compensation Expense |  | $ 147 | $ 220 | $ 214 |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized |  | 1,475,000 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant |  | 422,000 |  |  |
Percentage of Salary to Purchase Common Stock, Maximum |  | 15.00% |  |  |
Percentage of Common Stock Shares, Beginning |  | 85.00% |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee |  | 3,000 |  |  |
Shar-based Compensation Arrangement by Shar-based Payment Award, Maximum Number of Shares Per Employee, Amount |  | $ 25 |  |  |
Stock Issued During Period, Shares, Employee Stock Purchase Plans |  | 75,000 | 41,000 | 49,000 |
Employee Stock Ownership Plan (ESOP), Weighted Average Purchase Price of Shares Purchased |  | $ 4.36 | $ 8.65 | $ 6.29 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |  | $ 1.95 | $ 4.93 | $ 4.41 |

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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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