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Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 12 Months Ended
--- | --- | ---
Feb. 08, 2021 | Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020
Class of Stock [Line Items] |  |  |  |
Dividend rate | 4.875% |  |  |
Proceeds from issuance of preferred stock, net |  | $ 0 | $ 293,325 | $ 0
Stock repurchased (in shares) |  | 92,774 | 10,810,113 |
Additional shares authorized to be repurchased (in shares) |  | 3,724,344 |  |
Public Offering |  |  |  |
Class of Stock [Line Items] |  |  |  |
Number of shares issued in transaction (in shares) | 12,000,000 |  |  |
Public offering price (in usd per share) | $ 25.00 |  |  |
Public Offering | Series A Preferred Stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Number of shares issued in transaction (in shares) | 300,000 |  |  |
Weighted average |  |  |  |
Class of Stock [Line Items] |  |  |  |
Weighted average cost of repurchased stock (in dollars per share) |  | $ 35.14 | $ 32.25 |

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