Note 8 - Stock-based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 30, 2018 |
Dec. 31, 2017 |
Jan. 01, 2017 |
|
| Balance, outstanding options (in shares) | 576,023 | 1,090,126 | 479,564 |
| Balance, outstanding weighted average stock price (in dollars per share) | $ 1.13 | $ 1.22 | $ 1.88 |
| RSU granted (in shares) | 54,811 | 229,950 | 987,764 |
| RSU granted (in dollars per share) | $ 3.09 | $ 1.50 | $ 0.84 |
| RSU forfeited (in shares) | (75,151) | (261,606) | (352,077) |
| RSU forfeited (in dollars per share) | $ 0.91 | $ 0.89 | $ 0.87 |
| RSU converted into common shares (in shares) | (198,306) | (482,447) | (25,125) |
| RSU converted into common shares (in dollars per share) | $ 1.82 | $ 1.72 | $ 1.99 |
| Balance, outstanding weighted average remaining contractual term (Year) | 1 year 76 days | 1 year 306 days | 1 year 3 days |
| Balance, outstanding options (in shares) | 357,377 | 576,023 | 1,090,126 |
| Balance, outstanding weighted average stock price (in dollars per share) | $ 0.96 | $ 1.13 | $ 1.22 |
| X | ||||||||||
- Definition Weighted average per share amount of restricted stock units converted into common stock. No definition available.
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| X | ||||||||||
- Definition The weighted average stock price under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event. No definition available.
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| X | ||||||||||
- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average remaining contractual term for equity-based awards excluding options, 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
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| X | ||||||||||
- Definition Number of shares under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Net number of non-option equity instruments granted to participants. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number of shares issued during the period as a result of the conversion of convertible securities. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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