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Loans and Allowance for Loan Losses - Narrative (Details) - USD ($) | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Jun. 30, 2025 | Dec. 31, 2024 | Jun. 30, 2024 | Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |  |  |
Total loans | $ 43,753,234,000 |  | $ 43,753,234,000 |  |  | $ 42,609,028,000 |  |
Land held for future development, period |  |  | 1 year |  |  |  |  |
Financing receivable, allowance for credit loss | 469,521,000 | $ 484,985,000 | $ 469,521,000 | $ 484,985,000 | $ 464,831,000 | 486,845,000 | $ 485,101,000 | $ 479,385,000
Reserve for unfunded commitments | 50,700,000 |  | 50,700,000 |  |  | 52,500,000 |  |
All financing receivable, allowance for credit loss | $ 520,300,000 |  | 520,300,000 |  |  | $ 539,300,000 |  |
Increase (decrease) in allowance for credit loss |  |  | $ (19,000,000) |  |  |  |  |
ACL to loans ratio (as percent) | 1.19% |  | 1.19% |  |  | 1.27% |  |
Allowance for credit loss, reasonable and supportable forecast period (in year) |  |  | 2 years |  |  |  |  |
Allowance for credit loss, straight-line basis historical period (in year) |  |  | 1 year |  |  |  |  |
Allowance for credit loss, measurement input, estimated peak weighted average unemployment rate | 4.70% |  | 4.70% |  |  | 4.60% |  |
Financing receivable, modified, subsequent default | $ 0 | $ 0 | $ 0 | $ 74,700,000 |  |  |  |
Commitments to land additional funds to TDRs | 0 |  | $ 0 |  |  | $ 0 |  |
Substandard |  |  |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |  |  |
Retail loan substandard period (in days) |  |  | 90 days |  |  |  |  |
Loss |  |  |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |  |  |
Retail loan charge off (in days) |  |  | 120 days |  |  |  |  |
Asset Pledged as Collateral |  |  |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |  |  |
Total loans | $ 23,280,000,000 |  | $ 23,280,000,000 |  |  | $ 24,660,000,000 |  |

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