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Borrowings and Other Obligations - Lines of Credit (Details) - Line of credit - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
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Federal Reserve Bank of San Francisco | Federal Reserve Bank Term Funding Program |  |
Line of Credit Facility [Line Items] |  |
Lines of credit | $ 326.3 | $ 358.0
FHLB short-term borrowings |  |
Line of Credit Facility [Line Items] |  |
Lines of credit | 931.4 | 948.1
FRBSF federal funds purchased | Unsecured debt |  |
Line of Credit Facility [Line Items] |  |
Lines of credit | $ 125.0 | $ 125.0

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