Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
Mar. 31, 2026 |
Dec. 31, 2025 |
Mar. 31, 2025 |
Dec. 31, 2024 |
|
| Entity Information [Line Items] | ||||||||
| Off-Balance Sheet, Credit Loss, Liability | $ 6.9 | $ 4.8 | $ 6.9 | $ 4.8 | $ 5.8 | $ 5.9 | $ 5.1 | $ 5.2 |
| Provision for (reduction of) credit loss expense | 3.9 | (0.1) | (2.9) | (20.3) | ||||
| Credit Extension Commitments | 2,553.9 | 2,553.9 | 2,638.8 | |||||
| Standby Letter of Credit | ||||||||
| Entity Information [Line Items] | ||||||||
| Credit Extension Commitments | 60.3 | 60.3 | $ 60.4 | |||||
| Cumulative effect, period of adoption, adjusted balance | ||||||||
| Entity Information [Line Items] | ||||||||
| Provision for (reduction of) credit loss expense | $ 1.1 | $ (0.3) | $ 1.0 | $ (0.4) | ||||