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Common Stock and Options - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  |  |  | 1 Months Ended | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 25, 2018 | Sep. 07, 2018 | Sep. 05, 2018 | Dec. 31, 2016 | Nov. 30, 2017 | Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016 | Oct. 03, 2018 | May 31, 2017 | Mar. 31, 2017 | Feb. 17, 2017 | Sep. 30, 2015 | Sep. 30, 2013
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares authorized to be repurchased (up to) |  |  |  |  |  |  |  | 7,000,000 |  |  | 2,000,000 | 5,000,000 | 50,000 | 170,000 | 105,000
Total stock compensation expense |  |  |  |  |  | $ 824 | $ 2,613 | $ 1,653 |  |  |  |  |  |  |
Granted (in shares) |  |  |  |  |  | 10,000 | 300,000 | 750,000 |  |  |  |  |  |  |
Shares issued (in dollars per share) |  |  |  |  |  |  |  |  |  | $ 34.00 |  |  |  |  |
Common shares available |  |  |  |  |  | 227,500 | 675,000 | 750,000 |  |  |  |  |  |  |
Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  | 2 years 6 months |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  |  |  | 5,000 | 0 | 5,000 | 0 |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  |  |  | $ 31.95 | $ 0 | $ 31.95 | $ 0 |  |  |  |  |  |  |
Total stock compensation expense |  |  |  |  |  | $ 104 | $ 137 | $ 264 |  |  |  |  |  |  |
Unrecognized expense |  |  |  |  |  | $ 69 | $ 172 |  |  |  |  |  |  |  |
Unrecognized compensation cost, expected recognition period |  |  |  |  |  | 9 months |  |  |  |  |  |  |  |  |
Number of shares vested |  |  |  |  |  | 1,667 | 3,001 | 4,933 |  |  |  |  |  |  |
Aggregate value of shares vested |  |  |  |  |  | $ 53 |  |  |  |  |  |  |  |  |
Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total stock compensation expense |  |  |  |  |  | 674 | $ 1,617 | $ 616 |  |  |  |  |  |  |
Unrecognized expense |  |  |  |  |  | $ 502 | $ 2,174 |  |  |  |  |  |  |  |
Unrecognized compensation cost, expected recognition period |  |  |  |  |  | 1 year 3 months 14 days |  |  |  |  |  |  |  |  |
2019 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued (in dollars per share) | $ 33.34 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |
Period following an executive's termination of employment for a number of reasons | 18 months |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period following an executive's termination of employment without cause | 12 months |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  | $ 34.02 |  |  |  |  |  |  |  |  |
2019 Option Grants | John Kiernan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Granted (in shares) | 10,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
2019 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of awards vesting (in shares) | 3,333 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days | 20 days |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) | $ 40.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |
2019 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of awards vesting (in shares) | 3,333 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days | 20 days |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) | $ 45.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |
2019 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of awards vesting (in shares) | 3,334 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days | 20 days |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) | $ 50.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |
2019 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  | 7.10 |  |  |  |  |  |  |  |  |
2019 Option Grants | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  | $ 40.00 |  |  |  |  |  |  |  |  |
2018 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total stock compensation expense |  |  |  |  |  | $ (823) |  |  |  |  |  |  |  |  |
Shares issued (in dollars per share) |  | $ 33.60 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |
Period following an executive's termination of employment for a number of reasons |  | 18 months |  |  |  |  |  |  |  |  |  |  |  |  |
Period following an executive's termination of employment without cause |  | 12 months |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  | $ 34.02 |  |  |  |  |  |  |  |  |
2018 Option Grants | John Kiernan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Granted (in shares) |  | 90,000 |  |  |  |  |  |  |  |  |  |  |  |  |
2018 Option Grants | Remy W. Trafelet |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Granted (in shares) |  | 210,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Award expiration period |  |  |  |  |  | 6 months |  |  |  |  |  |  |  |  |
2018 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  | $ 35.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |
2018 Option Grants | Tranche One | Remy W. Trafelet |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  | 20 days |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  | $ 35.00 |  |  |  |  |  |  |  |  |
Number of shares expected to vest |  |  |  |  |  | 26,250 |  |  |  |  |  |  |  |  |
2018 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  | $ 40.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |
2018 Option Grants | Tranche Two | Remy W. Trafelet |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  | 20 days |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  | $ 40.00 |  |  |  |  |  |  |  |  |
Number of shares expected to vest |  |  |  |  |  | 26,250 |  |  |  |  |  |  |  |  |
2018 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  | $ 45.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |
2018 Option Grants | Tranche Four |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  | $ 50.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |
2018 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  |  | $ 7.40 |  |  |  |  |  |  |  |
2018 Option Grants | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  | $ 35.00 |  |  |  |  |  |  |  |  |
2016 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrecognized expense |  |  |  |  |  |  | $ 783 |  |  |  |  |  |  |  |
Shares issued (in dollars per share) |  |  |  | $ 27.15 |  |  |  |  |  |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  | 20 days |  |  |  |  |  |  |  |  |  |  |
Period following an executive's termination of employment for a number of reasons |  |  |  | 18 months |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  | $ 34.02 |  |  |  |  |  |  |  |  |
2016 Option Grants | Remy W. Trafelet |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  |  | 300,000 |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | Henry R. Slack |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  |  | 225,000 |  |  |  |  |  |  |  |  |  |  |
Shares forfeited |  |  | 187,500 |  |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | George R. Brokaw |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Granted (in shares) |  |  |  | 225,000 |  |  |  |  |  |  |  |  |  |  |
Shares forfeited |  |  | 187,500 |  |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  | $ 60.00 |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  | $ 75.00 |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  | $ 90.00 |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | Tranche Four |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  | $ 105.00 |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |
2016 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  |  |  |  | $ 3.53 |  |  |  |  |  |
2016 Option Grants | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  | 60.00 |  |  |  |  |  |  |  |  |
2019 Modified Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  | $ 1.40 |  |  |  |  |  |  |  |  |
2015 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares authorized to be repurchased (up to) |  |  |  |  |  | 1,250,000 |  |  |  |  |  |  |  |  |
2015 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common shares available |  |  |  |  |  | 1,005,000 |  |  |  |  |  |  |  |  |
2015 Option Grants | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  |  | 1 year |  |  |  |  |  |  |  |  |
2015 Option Grants | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  |  | 6 years |  |  |  |  |  |  |  |  |

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