Commitments and Credit Risk (Details) - USD ($) |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2026 |
Dec. 31, 2025 |
|
| Other Commitments [Line Items] | ||
| Commitments to originate fixed-rate mortgage loans, term | 30 days | |
| Outstanding letters of credit | $ 944,400,000 | $ 785,400,000 |
| Term of letter of credit | 1 year | 1 year |
| Standby Letters of Credit | ||
| Other Commitments [Line Items] | ||
| Outstanding letters of credit | $ 82,300,000 | $ 72,900,000 |
| Deferred revenue | $ 0 | $ 0 |
| Standby Letters of Credit | Minimum | ||
| Other Commitments [Line Items] | ||
| Term of letter of credit | 9 months | 9 months |
| Standby Letters of Credit | Maximum | ||
| Other Commitments [Line Items] | ||
| Term of letter of credit | 15 years | 15 years |
| Credit Card Commitments | ||
| Other Commitments [Line Items] | ||
| Outstanding commitments | $ 795,800,000 | $ 799,400,000 |
| Other Loan Commitments | ||
| Other Commitments [Line Items] | ||
| Outstanding commitments | 4,720,000,000 | 4,190,000,000 |
| Fixed Rate Mortgage Loans | ||
| Other Commitments [Line Items] | ||
| Outstanding commitments | $ 28,400,000 | $ 20,500,000 |