v3.25.1

Stockholders' equity - Narrative (Details) - USD ($) | Jan. 31, 2025 | Sep. 30, 2024
--- | --- | ---
Share Repurchase Program [Line Items] |  |
Share repurchase program, authorized amount |  | $ 300,000,000
Remaining authorized repurchase amount | $ 177,800,000 |
Passive Custodial Funds |  |
Share Repurchase Program [Line Items] |  |
Minimum net worth above custodial assets (as a percent) | 2.00% |
Non-passive Custodial Fund |  |
Share Repurchase Program [Line Items] |  |
Minimum net worth above custodial assets (as a percent) | 4.00% |

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