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Business Combination - Schedule of Pro Forma Information (Details) - Luther Burbank - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2024 | Sep. 30, 2023
Business Acquisition [Line Items] |  |
Net-interest income | $ 710,644 | $ 833,957
Non-interest income | 63,371 | 56,331
Net income | $ 207,689 | $ 291,832

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