Stock Based Compensation, Non-Vested Performance-Based Stock Rights (Details) - Stock Incentive Plan [Member] - Performance-Based Stock Rights [Member] - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock Based Compensation [Abstract]
Award vesting period			3 years
Unrecognized compensation cost	$ 227,000	$ 234,000	$ 227,000	$ 234,000
Non-Vested Performance-Based Stock Rights [Roll Forward]
Nonvested at beginning of period (in shares)			18,062	18,045
Granted (in shares)			6,867	10,525
Vested (in shares)			0	0
Forfeited (in shares)			(2,826)	(3,984)
Nonvested at end of period (in shares)	22,103	24,586	22,103	24,586
Non-Vested Performance-Based Stock Rights, Weighted Average Fair Value Per Share [Roll Forward]
Nonvested at beginning of period (in dollars per share)			$ 16.44	$ 15.72
Granted (in dollars per share)			21.47	17.50
Vested (in dollars per share)			0	0
Forfeited (in dollars per share)			21.47	15.75
Nonvested at end of period (in dollars per share)	$ 17.90	$ 16.49	$ 17.90	$ 16.49
Certain Executive Officers [Member]
Stock Based Compensation [Abstract]
Compensation expense	$ 21,000	$ 28,000	$ 40,000	$ 42,000
Non-Vested Performance-Based Stock Rights [Roll Forward]
Granted (in shares)			6,867	10,525

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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