Note 6 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares |
9 Months Ended | 12 Months Ended | |
|---|---|---|---|
Dec. 31, 2017 |
Jan. 01, 2017 |
Apr. 02, 2017 |
|
| Outstanding, Weighted-average exercise price, beginning balance (in dollars per share) | $ 8.35 | $ 7.64 | $ 7.64 |
| Outstanding, Shares, beginning balance (in shares) | 322,500 | 305,000 | 305,000 |
| Granted, Weighted-average exercise price (in dollars per share) | $ 7.35 | $ 9.60 | |
| Number of options issued (in shares) | 140,000 | 120,000 | |
| Exercised, Weighted-average exercise price (in dollars per share) | $ 7.67 | ||
| Exercised, Shares (in shares) | (102,500) | ||
| Forfeited, Weighted-average exercise price (in dollars per share) | $ 9.05 | ||
| Forfeited, Shares (in shares) | (67,500) | ||
| Outstanding, Weighted-average exercise price, ending balance (in dollars per share) | $ 7.93 | $ 8.35 | $ 8.35 |
| Outstanding, Shares, ending balance (in shares) | 395,000 | 322,500 | 322,500 |
| Exercisable, Weighted-average exercise price (in dollars per share) | $ 7.94 | $ 7.33 | |
| Exercisable, Shares (in shares) | 220,000 | 147,500 | |
| 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://www.xbrl.org/2003/role/presentationRef
|
| 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://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| 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://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
|
| X | ||||||||||
- Definition Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. No definition available.
|
| X | ||||||||||
- Definition Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
|
| X | ||||||||||
- Definition Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|