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Note 9 - Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | 12 Months Ended
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Sep. 28, 2019 | Sep. 29, 2018 | Sep. 30, 2017 | Oct. 01, 2016
Options outstanding, balance (in shares) | 264 | 392 |  | 371
Weighted average exercise price per share (in dollars per share) | $ 29.25 | $ 23.40 |  | $ 20.81
Options outstanding, granted (in shares) | 129 | 77 | 88 |
Weighted average exercise price per share, granted (in dollars per share) | $ 19.74 | $ 34.84 | $ 30.93 |
Options outstanding, exercised (in shares) | (5) | (196) | (67) |
Weighted average exercise price per share, exercised (in dollars per share) | $ 23.95 | $ 19.68 | $ 19.05 |
Aggregate intrinsic value, exercised | $ 21 | $ 3,866 | $ 1,212 |
Options outstanding, Forfeited (in shares) |  | (9) |  |
Weighted average exercise price per share, forfeited (in dollars per share) |  | $ 29.88 |  |
Options outstanding, balance (in shares) | 388 | 264 | 392 |
Weighted average exercise price per share (in dollars per share) | $ 26.16 | $ 29.25 | $ 23.40 |
Contractual term - weighted average, balance (Year) | 7 years 295 days |  |  |
Aggregate intrinsic value, outstanding | $ 370 |  |  |
Options outstanding, vested and anticipated to vest in future (in shares) | 384 |  |  |
Weighted average exercise price per share, vested and anticipated to vest in future (in dollars per share) | $ 26.17 |  |  |
Contractual term - weighted average, vested and anticipated to vest in future (Year) | 7 years 288 days |  |  |
Aggregate intrinsic value, vested and anticipated to vest in future | $ 366 |  |  |
Options outstanding, exercisable (in shares) | 184 |  |  |
Weighted average exercise price per share, exercisable (in dollars per share) | $ 27.62 |  |  |
Contractual term - weighted average, exercisable (Year) | 6 years 113 days |  |  |
Aggregate intrinsic value, exercisable | $ 195 |  |  |
Minimum [Member] |  |  |  |
Exercise price per share, balance, lower (in dollars per share) | $ 10.23 | 10.23 | 9.16 | 9.16
Exercise price per share, granted, lower (in dollars per share) | 18.25 | 29.69 | 26.75 |
Exercise price per share, exercised, lower (in dollars per share) | 18.05 | 9.16 | 9.16 |
Exercise price per share, forfeited, lower (in dollars per share) |  | 23.95 |  |
Maximum [Member] |  |  |  |
Exercise price per share, balance, upper (in dollars per share) | 41.85 | 41.85 | 37.06 | $ 34.49
Exercise price per share, granted, upper (in dollars per share) | 21.57 | 41.85 | 37.06 |
Exercise price per share, exercised, upper (in dollars per share) | $ 26.75 | 37.06 | $ 23.95 |
Exercise price per share, forfeited, upper (in dollars per share) |  | $ 37.06 |  |

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- 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. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- 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. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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