Share-Based Plans - Restricted Stock Activity (Details) - USD ($)	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Shares
Nonvested, beginning of period (in shares)	145,677
Nonvested, end of period (in shares)	135,754
Restricted Stock
Shares
Nonvested, beginning of period (in shares)	145,677	140,577
Granted (in shares)	10,655	15,930
Vested (in shares)	(19,408)	(14,270)
Cancelled (in shares)	(1,170)	(2,200)
Nonvested, end of period (in shares)	135,754	140,037
Weighted-Average Grant Date Fair Value
Nonvested, beginning of period (in dollars per share)	$ 48.88	$ 48.57
Granted (in dollars per share)	59.00	50.57
Vested (in dollars per share)	52.34	51.24
Cancelled (in dollars per share)	50.54	48.11
Nonvested, end of period (in dollars per share)	$ 49.16	$ 48.57
Additional information
Compensation expense	$ 474,000	$ 511,000
Compensation expense after tax	296,000	$ 365,000
Unrecognized compensation expense	$ 3,610,000
Restricted Stock \| Employees
Summary of restricted stock awards
Vesting period	5 years
Restricted Stock \| Nonemployee Directors
Summary of restricted stock awards
Vesting period	3 years

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Amount, after tax, of expense for award under share-based payment arrangement.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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