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Securities Available for Sale and Held to Maturity - Additional Information (Details) - USD ($) | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024 | Dec. 31, 2024 | Dec. 31, 2022
Schedule of Available For Sale and Held to Maturity Securities [Line Items] |  |  |  |  |  |
Reclassification of Securities available for sale to securities held to maturity |  |  |  |  |  | $ 766,000,000
Net unrealized holding loss on AFS Securities at date of transfer |  |  |  |  |  | 91,900,000
Net unrealized holding losses on AFS Securities, net of tax at date of transfer |  |  |  |  |  | $ (68,900,000)
Net unamortized, unrealized loss on transfer of securities | $ 41,500,000 |  | $ 41,500,000 |  | $ 46,600,000 |
Credit loss recognized | 0 |  | 0 |  | 0 |
Expected credit losses, current. |  |  | 0 |  | 0 |
Reserve for securities held to maturity | 0 |  | 0 |  | 0 |
Securities held to maturity | 1,290,572,000 |  | 1,290,572,000 |  | 1,335,385,000 |
Securities available for sale | 1,782,092,000 |  | 1,782,092,000 |  | 1,692,534,000 |
Available for sale securities, average yield |  | 4.85% |  | 4.85% |  |
Gross realized losses | 0 | $ (182,792,000) | 0 | $ (182,792,000) |  |
Net unamortized, unrealized loss on transfer of securities, net of tax |  | 137,100,000 |  | 137,100,000 |  |
Purchases of securities available for sale |  | 1,378,000,000 | 137,765,000 | 1,382,457,000 |  |
Pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law | 1,783,000,000 |  | 1,783,000,000 |  | 1,910,000,000 |
Pledged securities providing additional contingency funding | 0 |  | 0 |  | 0 |
Past Due 30 to 59 Days [Member] |  |  |  |  |  |
Schedule of Available For Sale and Held to Maturity Securities [Line Items] |  |  |  |  |  |
Securities held to maturity | 0 |  | 0 |  | 0 |
Securities Available for Sale [Member] |  |  |  |  |  |
Schedule of Available For Sale and Held to Maturity Securities [Line Items] |  |  |  |  |  |
Accrued interest receivable | 5,600,000 |  | 5,600,000 |  | 5,000,000 |
Securities Held to Maturity [Member] |  |  |  |  |  |
Schedule of Available For Sale and Held to Maturity Securities [Line Items] |  |  |  |  |  |
Accrued interest receivable | 2,300,000 |  | 2,300,000 |  | 2,400,000 |
Held-to-maturity nonnaccrual | $ 0 |  | $ 0 |  | $ 0 |
Investment Securities Portfolio [Member] |  |  |  |  |  |
Schedule of Available For Sale and Held to Maturity Securities [Line Items] |  |  |  |  |  |
Securities available for sale |  | $ 1,561,000,000 |  | $ 1,561,000,000 |  |
Available for sale securities, average yield |  | 1.36% |  | 1.36% |  |

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