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Note 12 - Stock Options and Employee Stock Purchase Plan (Details) - Summary of Stock Options (USD $)
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12 Months Ended |
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Dec. 31, 2014
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Dec. 31, 2011
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Dec. 31, 2013
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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| Exericse price range, lower limit (in Dollars per share) |
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$ 10.86 |
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| Exercise price (in Dollars per share) |
$ 5.89 |
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$ 5.48 |
| Exercise price range, upper limit (in Dollars per share) |
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$ 36.66 |
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| Options outstanding |
2,847,097 |
|
1,957,069 |
| Weighted average contractual life |
8 years 237 days |
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| Options exercisable |
897,294 |
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| Exercise Price Range 1 [Member] |
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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|
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| Exercise price (in Dollars per share) |
$ 4.20 |
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| Options outstanding |
553,434 |
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| Weighted average contractual life |
6 years 233 days |
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| Options exercisable |
521,718 |
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| Exercise Price Range 2 [Member] |
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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| Exercise price (in Dollars per share) |
$ 5.82 |
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| Options outstanding |
1,219,689 |
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| Weighted average contractual life |
8 years 310 days |
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| Options exercisable |
333,785 |
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| Exercise Price Range 3 [Member] |
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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| Exericse price range, lower limit (in Dollars per share) |
$ 5.98 |
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| Exercise price range, upper limit (in Dollars per share) |
$ 6.62 |
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| Options outstanding |
869,525 |
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| Weighted average contractual life |
9 years 6 months |
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| Exercise Price Range 4 [Member] |
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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| Exericse price range, lower limit (in Dollars per share) |
$ 7.32 |
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| Exercise price range, upper limit (in Dollars per share) |
$ 11.09 |
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| Options outstanding |
203,172 |
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| Weighted average contractual life |
9 years 36 days |
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| Options exercisable |
40,514 |
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| Exercise Price Range 5 [Member] |
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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| Exericse price range, lower limit (in Dollars per share) |
$ 35.30 |
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| Exercise price range, upper limit (in Dollars per share) |
$ 36.66 |
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| Options outstanding |
1,271 |
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| Weighted average contractual life |
6 years 255 days |
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| Options exercisable |
1,271 |
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| Exercise Price Range 6 [Member] |
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| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
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| Exericse price range, lower limit (in Dollars per share) |
$ 135.78 |
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| Exercise price range, upper limit (in Dollars per share) |
$ 4,615.92 |
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| Options outstanding |
6 |
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| Weighted average contractual life |
302 days |
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| Options exercisable |
6 |
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