Stock-Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable (in shares)	112,319	100,824	89,561
Options exercisable, weighted average exercise price (in USD per share)	$ 28.17	$ 26.50	$ 24.48
Total intrinsic value of stock options outstanding and exercisable	$ 1,100,000	$ 646,000	$ 670,000
Stock-based compensation expense	$ 832,000	816,000	665,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation options contractual term	10 years
Stock incentive plan vesting period, years	3 years
Total intrinsic value of stock options exercised	$ 203,000	383,000	631,000
Amount withheld for stock option exercises and related income taxes	317,000	227,000	1,100,000
Stock-based compensation expense	143,000	183,000	152,000
Unrecognized compensation expense	$ 276,000
Weighted-average period for recognition of expense	2 years 1 month 25 days
Cash Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from exercise of stock options	$ 0	195,000	69,000
Cashless Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from exercise of stock options	$ 282,000	193,000	954,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan vesting period, years	3 years
Total intrinsic value of stock options exercised	$ 906,000	654,000	676,000
Stock-based compensation expense	689,000	$ 633,000	$ 513,000
Unrecognized compensation expense	$ 1,700,000
Weighted-average period for recognition of expense	2 years 1 month 28 days
Prior Stock Option Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of authorized stock for stock incentive plan (in shares)	0
2017 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of authorized stock for stock incentive plan (in shares)	350,000

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Withheld Shares For Company Expenses

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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Amount of noncash expense for share-based payment arrangement.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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