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Common Stock and Options - Narrative (Details) - USD ($) |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 06, 2022 | May 31, 2022 | May 18, 2022 | Apr. 01, 2022 | Jan. 26, 2022 | Nov. 05, 2021 | Oct. 15, 2021 | Nov. 10, 2020 | Oct. 11, 2019 | Feb. 11, 2019 | Oct. 25, 2018 | Sep. 07, 2018 | Dec. 31, 2016 | Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020 | Feb. 27, 2015
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total stock-based compensation expense |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,235,000 | $ 1,230,000 | $ 1,306,000 |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | 0 | 118,000 |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |
Common shares available |  |  |  |  |  |  |  |  |  |  |  |  |  | 126,500 | 218,000 | 293,000 |
Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total stock-based compensation expense |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 459,000 | $ 144,000 | $ 69,000 |
Number of restricted shares awarded |  |  |  |  |  |  |  |  |  |  |  |  |  | 30,227 | 5,885 |  |
Weighted average fair value (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 37.82 | $ 31.20 |  |
Number of restricted shares vested |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,740 | 0 | 5,666 |
Number of restricted shares forfeited |  |  |  |  |  |  |  |  |  |  |  |  |  | 826 |  |  |
Unrecognized expense |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 692,000 | $ 40,000 |  |
Aggregate value of shares vested |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 251,000 |
Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total stock-based compensation expense |  |  |  |  |  |  |  |  |  |  |  |  |  | 115,000 | 242,000 | 504,000 |
Unrecognized expense |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 18,000 | 134,000 |  |
Unrecognized compensation cost, expected recognition period |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 months |  |  |
Board of Directors Fees |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total stock-based compensation expense |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 661,000,000 | $ 844,000,000 | $ 733,000,000 |
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  | $ 35.00 |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,092,000 |  |  |
2015 Option Grants | Chief Financial Officer | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded | 747 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) | $ 33.50 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2015 Option Grants | Chief Executive Officer | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  | 12,500 | 5,000 |  |  | 2,500 |  |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  | $ 40.17 | $ 37.98 |  |  | $ 34.41 |  |  |  |  |  |  |  |  |  |
2015 Option Grants | President | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  | 12,500 | 5,000 |  |  | 2,500 |  |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  | $ 40.17 | $ 37.98 |  |  | $ 34.41 |  |  |  |  |  |  |  |  |  |
2015 Option Grants | Employees | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  |  |  | 7,256 |  |  |  |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  |  |  | $ 35.50 |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares vested |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,144 |  |  |
2015 Option Grants | Executive Officer | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  |  |  |  | 2,224 |  |  |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  |  |  |  | $ 37.13 |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares forfeited |  | 674 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2015 Option Grants | Other Executives | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  |  |  |  |  |  | 5,885 |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  |  |  |  |  |  | $ 31.20 |  |  |  |  |  |  |  |  |
2015 Option Grants | Senior Managers | Restricted Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of restricted shares awarded |  |  |  |  |  | 2,224 |  | 5,885 |  |  |  |  |  |  |  |  |
Weighted average fair value (in dollars per share) |  |  |  |  |  | $ 37.13 |  | $ 31.20 |  |  |  |  |  |  |  |  |
2015 Option Grants | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 year |  |
2015 Option Grants | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6 years |  |
2020 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  | 118,000 |  |  |  |  |  |  |  |
Shares issued (in dollars per share) |  |  |  |  |  |  |  |  | $ 33.96 |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |
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 |  |  |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |
2020 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  | $ 35.00 |  |  |  |  |  |  |  |
2020 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  | $ 40.00 |  |  |  |  |  |  |  |
2020 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  | $ 45.00 |  |  |  |  |  |  |  |
2020 Option Grants | Tranche Four |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  | $ 50.00 |  |  |  |  |  |  |  |
2020 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3.20 |  |
2020 Option Grants | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 40.00 |  | $ 35.00 |
2020 Option Grants | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 35.00 |
2019 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued (in dollars per share) |  |  |  |  |  |  |  |  |  |  | $ 33.34 |  |  |  |  |  |
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 |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |
2019 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  | $ 40.00 |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  | 3,333 |  |  |  |  |  |
2019 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  | $ 45.00 |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  | 3,333 |  |  |  |  |  |
2019 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  | $ 50.00 |  |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  | 3,334 |  |  |  |  |  |
2019 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.10 |  |
2019 Option Grants | Chief Financial Officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  |  |  | 10,000 |  |  |  |  |  |
2019 Option Grants | Chief Executive Officer | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |
2019 Option Grants | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40.00 |  |
2018 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  | $ 33.60 |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |
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 |  |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |
2018 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  | $ 35.00 |  |  |  |  |
2018 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  | $ 40.00 |  |  |  |  |
2018 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  | $ 45.00 |  |  |  |  |
2018 Option Grants | Tranche Four |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  | $ 50.00 |  |  |  |  |
2018 Option Grants | Chief Financial Officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  |  |  |  | 90,000 |  |  |  |  |
2018 Option Grants | Chief Executive Officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  |  |  |  | 210,000 |  |  |  |  |
2018 Option Grants | Chief Executive Officer | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 (in shares) |  |  |  |  |  |  |  |  |  | 26,250 |  |  |  |  |  |  |
2018 Option Grants | Chief Executive Officer | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  | $ 40.00 |  |  |  |  |  |  |
Number of shares expected to vest (in shares) |  |  |  |  |  |  |  |  |  | 26,250 |  |  |  |  |  |  |
2018 Option Grants | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 35.00 |
2018 Option Grants | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 40.00 |  |  |
2016 Option Grants |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  | $ 27.15 |  |  |  |
Period following an executive's termination of employment for a number of reasons |  |  |  |  |  |  |  |  |  |  |  |  | 18 months |  |  |  |
Number of awards vesting (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |
2016 Option Grants | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  | $ 60.00 |  |  |  |
2016 Option Grants | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  | $ 75.00 |  |  |  |
2016 Option Grants | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  | $ 90.00 |  |  |  |
2016 Option Grants | Tranche Four |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of options |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |
Amount per share (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  | $ 105.00 |  |  |  |
2016 Option Grants | Chief Executive Officer |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  |  |  |  |  | 300,000 |  |  |  |
2016 Option Grants | Board of Directors Chairman |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee stock options granted (in shares) |  |  |  |  |  |  |  |  |  |  |  |  | 225,000 |  |  |  |
2016 Option Grants | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 60.00 |  |
2019 Option Grants | Options |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Grants in period, weighted average (in dollars per share) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.40 |  |
2019 Option Grants | Chief Executive Officer | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares forfeited (in shares) |  |  |  |  |  |  |  |  |  | 26,250 |  |  |  |  |  |  |
2019 Option Grants | Chief Executive Officer | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of consecutive trading days |  |  |  |  |  |  |  |  |  | 20 days |  |  |  |  |  |  |
Shares forfeited (in shares) |  |  |  |  |  |  |  |  |  | 26,250 |  |  |  |  |  |  |
2019 Option Grants | Maximum [Member] | Chief Executive Officer | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class Of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  |  |  |  |  |  |  |  |  | $ 40.00 |  |  |  |  |  |  |

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