Investment Securities - Debt Securities, Held-to-Maturity, Allowance for Credit Loss (Details)	6 Months Ended
	Jun. 30, 2023 USD ($)
Allowance for credit losses:
Beginning balance	$ 0
Credit loss expense (reduction)	(10,000)
Securities charged-off	0
Recoveries	0
Total ending allowance balance	428,000	[1]
Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses:
Beginning balance	438,000
State and political subdivisions
Allowance for credit losses:
Beginning balance	0
Credit loss expense (reduction)	(5,000)
Securities charged-off	0
Recoveries	0
Total ending allowance balance	224,000
State and political subdivisions | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses:
Beginning balance	229,000
Corporate securities
Allowance for credit losses:
Beginning balance	0
Credit loss expense (reduction)	(5,000)
Securities charged-off	0
Recoveries	0
Total ending allowance balance	204,000
Corporate securities | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses:
Beginning balance	$ 209,000

[1] December 31, 2022 and June 30, 2022 had no allowance for credit losses