Note 8 - Stock-based Compensation - Stock Option Transactions (Details) shares in Thousands |
3 Months Ended |
|---|---|
|
Mar. 31, 2018
$ / shares
shares
| |
| Outstanding, beginning of period (in shares) | shares | 2,344 |
| Outstanding, weighted average exercise price (in dollars per share) | $ / shares | $ 3.46 |
| Granted (in shares) | shares | 2,059 |
| Granted, weighted average exercise price (in dollars per share) | $ / shares | $ 2.96 |
| Outstanding, end of the period (in shares) | shares | 4,403 |
| Outstanding, weighted average exercise price (in dollars per share) | $ / shares | $ 3.18 |
| Outstanding, weighted average remaining contractual life (Year) | 8 years 182 days |
| Exercisable, end of the period (in shares) | shares | 2,453 |
| Exercisable, end of the Exercisable, weighted average exercise price (in dollars per share) | $ / shares | $ 3.63 |
| Exercisable, weighted average remaining contractual life (Year) | 7 years 292 days |
| X | ||||||||||
- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Gross number of share options (or share units) granted during the period. No definition available.
|
| X | ||||||||||
- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
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| X | ||||||||||
- Definition Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|