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Stock-based compensation - Narrative (Details) |  |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2023 shares | Jan. 08, 2023 USD ($) peer shares | Feb. 24, 2022 USD ($) peer shares | Feb. 08, 2021 USD ($) shares | Sep. 30, 2023 USD ($) shares | Sep. 30, 2022 USD ($) | Sep. 30, 2023 USD ($) shares | Sep. 30, 2022 USD ($) | Dec. 31, 2022 peer
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based payment arrangement, expense |  |  |  |  | $ 9,117,000 | $ 6,299,000 | $ 23,337,000 | $ 17,671,000 |
Number of peers | peer |  | 20 | 20 |  |  |  |  |  | 20
Share-based compensation arrangement by share-based payment award, vesting period |  |  |  |  |  |  | 4 years |  |
Options |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, options, outstanding, intrinsic value |  |  |  |  | 3,300,000 |  | $ 3,300,000 |  |
Share-based compensation arrangement by share-based payment award, options, exercises in period, intrinsic value |  |  |  |  | $ 500,000 |  | $ 3,300,000 |  |
Share-based compensation arrangement by share-based payment award, options, grants in period, gross (in shares) | shares |  |  |  |  | 0 |  | 0 |  |
Share-based compensation arrangement by share-based payment award, options, outstanding, weighted average remaining contractual term |  |  |  |  |  |  | 2 years 3 months 18 days |  |
Share-based payment arrangement, nonvested award, cost not yet recognized, amount |  |  |  |  | $ 0 |  | $ 0 |  |
Restricted Stock |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based payment arrangement, nonvested award, cost not yet recognized, amount |  |  |  |  | 33,000,000 |  | 33,000,000 |  |
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, fair value |  |  |  |  | 1,000,000 |  | 16,800,000 |  |
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, fair value |  |  |  |  | 5,000,000 |  | 16,900,000 |  |
Share-based payment arrangement, expense |  |  |  |  | 9,100,000 |  | $ 23,300,000 |  |
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition |  |  |  |  |  |  | 2 years 2 months 12 days |  |
Granted (in shares) | shares |  |  |  |  |  |  | 584,976 |  |
Market-based Restricted Stock |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based payment arrangement, nonvested award, cost not yet recognized, amount |  |  |  |  | 4,900,000 |  | $ 4,900,000 |  |
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, fair value |  |  |  | $ 1,300,000 |  |  |  |  |
Share-based payment arrangement, expense |  |  |  |  | $ 1,600,000 | 1,200,000 | $ 4,900,000 | 3,100,000 |
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition |  |  |  |  |  |  | 1 year 1 month 6 days |  |
Granted (in shares) | shares |  |  |  |  | 268,738 |  |  |  |
Share-based compensation arrangement by share-based payment award, percentage of awards | 100.00% |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, fair value assumptions, historical volatility rate |  | 78.00% | 63.00% | 68.00% |  |  |  |  |
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected dividend rate |  | 0.00% | 0.00% | 0.00% |  |  |  |  |
Share-based compensation arrangement by share-based payment award, fair value assumptions, risk free interest rate |  | 4.40% | 1.50% | 0.10% |  |  |  |  |
Share-based compensation arrangement by Share-based payment award, fair value assumptions, expected volatility rate period |  | 2 years | 2 years | 2 years |  |  |  |  |
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, aggregate fair value |  |  |  |  | $ 0 | $ 0 | $ 6,500,000 | 6,700,000 |
Share-based compensation arrangement by share-based payment award, equity instruments other than options, aggregate intrinsic value, vested |  |  |  |  |  |  | $ 700,000 | $ 5,000,000 |
Market-based Restricted Stock | Minimum |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, percentage of awards |  | 0.00% | 0.00% |  |  |  |  |  |
Market-based Restricted Stock | Maximum |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, percentage of awards |  | 200.00% | 200.00% |  |  |  |  |  |
Market-based Restricted Stock | Executive Officer |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based payment arrangement, expense |  | $ 6,800,000 | $ 6,700,000 |  |  |  |  |  |
Granted (in shares) | shares | 30,616 | 268,738 | 240,428 | 30,616 |  |  |  |  |

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