Commitments and Credit Risk (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Other Commitments [Line Items]
Outstanding letters of credit	$ 55,500,000	$ 44,400,000
Federal Home Loan Bank Certificates and Obligations (FHLB)
Other Commitments [Line Items]
Outstanding letters of credit	$ 339,500,000	$ 265,700,000
Term of letter of credit	1 year	1 year
Standby Letters of Credit
Other Commitments [Line Items]
Deferred revenue	$ 0	$ 0
Minimum
Other Commitments [Line Items]
Term of letter of credit	9 months
Maximum
Other Commitments [Line Items]
Term of letter of credit	15 years
Credit Card Commitments
Other Commitments [Line Items]
Outstanding commitments	$ 744,300,000	696,700,000
Other Loan Commitments
Other Commitments [Line Items]
Outstanding commitments	4,320,000,000	5,640,000,000
Fixed Rate Mortgage Loans
Other Commitments [Line Items]
Outstanding commitments	$ 24,600,000	$ 21,100,000