Commitments and Credit Risk (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Other Commitments [Line Items]
Commitments to originate fixed-rate mortgage loans, term (in days)	30 days
Outstanding letters of credit	$ 498,500,000	$ 1,120,000,000
Investment, Type [Extensible Enumeration]	Federal Home Loan Bank Certificates and Obligations (FHLB) [Member]	Federal Home Loan Bank Certificates and Obligations (FHLB) [Member]
Term of letter of credit	1 year	1 year
Standby Letters of Credit
Other Commitments [Line Items]
Outstanding letters of credit	$ 68,600,000	$ 41,600,000
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	$ 822,800,000	$ 756,900,000
Other Loan Commitments
Other Commitments [Line Items]
Outstanding commitments	4,270,000,000	4,030,000,000.00
Fixed Rate Mortgage Loans
Other Commitments [Line Items]
Outstanding commitments	$ 22,700,000	$ 17,800,000