Allowance for Credit Losses - Loan Modified to Borrowers Experiencing Financial Difficulty (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Troubled debt restructuring modifications
Amortized Cost Basis	$ 7,162,000	$ 794,000
Commitments related to borrowers experiencing financial difficulty	0
Aggregate commitments to extend credit, standby letters of credit and commercial letters of credit	6,500,000,000		$ 6,500,000,000
Commitments related to borrowers experiencing financial difficulty			$ 5,000,000.0
30 - 59 Days Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	96,000	9,000
60 - 89 Days Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	86,000
90 Days or Greater Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	22,000
Total Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	204,000	9,000
Current
Troubled debt restructuring modifications
Amortized Cost Basis	6,958,000	785,000
Commercial and Industrial
Troubled debt restructuring modifications
Amortized Cost Basis	467,000	96,000
Commercial and Industrial | Current
Troubled debt restructuring modifications
Amortized Cost Basis	467,000	96,000
Construction
Troubled debt restructuring modifications
Amortized Cost Basis	657,000	231,000
Construction | Current
Troubled debt restructuring modifications
Amortized Cost Basis	657,000	231,000
Commercial Real Estate
Troubled debt restructuring modifications
Amortized Cost Basis	2,857,000	4,000
Commercial Real Estate | Current
Troubled debt restructuring modifications
Amortized Cost Basis	2,857,000	4,000
Residential mortgage
Troubled debt restructuring modifications
Amortized Cost Basis	1,570,000	34,000
Residential mortgage | Current
Troubled debt restructuring modifications
Amortized Cost Basis	1,570,000	34,000
Consumer
Troubled debt restructuring modifications
Amortized Cost Basis	1,611,000	429,000
Consumer | 30 - 59 Days Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	96,000	9,000
Consumer | 60 - 89 Days Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	86,000
Consumer | 90 Days or Greater Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	22,000
Consumer | Total Past Due
Troubled debt restructuring modifications
Amortized Cost Basis	204,000	9,000
Consumer | Current
Troubled debt restructuring modifications
Amortized Cost Basis	1,407,000	420,000
Interest Rate Reduction
Troubled debt restructuring modifications
Amortized Cost Basis	628,000	362,000
Amortized Cost Basis of Modified Loans That Subsequently Defaulted	300,000	10,000
Interest Rate Reduction | Commercial Real Estate
Troubled debt restructuring modifications
Amortized Cost Basis		$ 4,000
Reduced weighted-average contractual interest rate		0.75%
Interest Rate Reduction | Consumer
Troubled debt restructuring modifications
Amortized Cost Basis	$ 628,000	$ 358,000
% of Total Class of Financing Receivable	0.06%	0.03%
Reduced weighted-average contractual interest rate	13.55%	13.51%
Amortized Cost Basis of Modified Loans That Subsequently Defaulted	$ 300,000	$ 10,000
Term Extension
Troubled debt restructuring modifications
Amortized Cost Basis	627,000	432,000
Amortized Cost Basis of Modified Loans That Subsequently Defaulted	7,000
Term Extension | Commercial and Industrial
Troubled debt restructuring modifications
Amortized Cost Basis	$ 199,000	$ 96,000
% of Total Class of Financing Receivable	0.01%
Added weighted-average years to the life of loans	3 years 9 months 18 days	3 years
Term Extension | Construction
Troubled debt restructuring modifications
Amortized Cost Basis		$ 231,000
% of Total Class of Financing Receivable		0.03%
Added weighted-average years to the life of loans		2 years 10 months 24 days
Term Extension | Residential mortgage
Troubled debt restructuring modifications
Amortized Cost Basis	$ 310,000	$ 34,000
% of Total Class of Financing Receivable	0.01%
Added weighted-average years to the life of loans	1 year	5 years 10 months 24 days
Term Extension | Consumer
Troubled debt restructuring modifications
Amortized Cost Basis	$ 118,000	$ 71,000
% of Total Class of Financing Receivable	0.01%	0.01%
Added weighted-average years to the life of loans	4 years 2 months 12 days	4 years 7 months 6 days
Amortized Cost Basis of Modified Loans That Subsequently Defaulted	$ 7,000
Other-Than-Insignificant Payment Delay
Troubled debt restructuring modifications
Amortized Cost Basis	1,260,000
Other-Than-Insignificant Payment Delay | Residential mortgage
Troubled debt restructuring modifications
Amortized Cost Basis	$ 1,260,000
% of Total Class of Financing Receivable	0.03%
Financing receivable, modified, increase (decrease) from modification	$ 172,000