Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount

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- Definition

Number of Individual Stock Incentive Plans

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Proceeds exercise of stock options, net of stock swaps

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Share-based Compensation Arrangement by Share-based Payment Award, Expiration Term for Participant Owning More than Set Threshold of Common Stock

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Ownership of Common Stock by Participant, Threshold Causing Greater Price on Stock Option Granted

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Price of Stock Options Granted to Fair Market Value for Participant Owning More than Set Threshold of Common Stock, Percentage

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Price of Stock Options Granted to Fair Market Value, Percentage

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- Definition

Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

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- Definition

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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- Definition

Unrecognized cost of unvested share-based compensation awards.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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- Definition

Noninterest expense related to directors' fees which are fees paid by an Entity to its directors. Directors' fees may be paid in addition to salary and other benefits.

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- Definition

Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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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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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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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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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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- Definition

Price of a single share of a number of saleable stocks of a company.

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- Definition

Percentage of vesting of share-based compensation awards.

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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- Definition

Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders.

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Stock-Based Compensation - Stock Options, Stock Awards, and Stock in Lieu of Directors' Fees (Details) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Jan. 31, 2018 shares	Jan. 31, 2017 shares	Jan. 31, 2016 shares	Dec. 31, 2017 USD ($) plans shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jan. 03, 2017 $ / shares	Jan. 04, 2016 $ / shares	Jan. 02, 2015 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of individual stock incentive plans \| plans				2
Shares remain available for future grants under the 2009 plan \| shares				465,198
Stock-based compensation expense				$ 1,753	$ 2,380	$ 1,803
Tax benefit recognized related to stock-based compensation expense				716	972	720
Income tax benefit for stock compensation in income statement				$ 922	0	0
Tax benefit from stock compensation					789	217
Price as a percentage of fair market value that stock options may not be granted below				100.00%
Percentage of ownership of common stock by participants that if greater causes greater grant price				10.00%
Price as a percentage of fair market value that stock options may not be granted below for anyone who owns more than 10% common stock				110.00%
Expiration period of options granted for those who own more than 10% common stock				5 years
Proceeds from stock option exercises				$ 355	546	431
Total intrinsic value of options exercised				1,600	1,000	396
Cash paid by the Company to net settle employee taxes on restricted stock and options				931	442	0
Fair value of options vested				246	237	359
Directors fee expense				747	661	424
Number of shares issued in lieu of cash to directors \| shares		12,992	10,657
Fair market share price \| $ / shares							$ 38.39	$ 22.04	$ 23.86
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in lieu of cash to directors \| shares	7,326
Non-Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax benefit recognized related to stock-based compensation expense				115	117	102
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				204	267	318
Tax benefit recognized related to stock-based compensation expense				$ 83	$ 109	$ 127
Term in years				10 years	10 years	10 years
Cash paid by the Company to net settle employee taxes on restricted stock and options				$ 386	$ 158
Unrecognized stock-based compensation expense				$ 339
Remaining vesting period unrecognized compensation expense is to be recognized				2 years 3 months 18 days
Restricted Stock and Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 1,300	1,800	$ 1,200
Tax benefit recognized related to stock-based compensation expense				518	746	491
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash paid by the Company to net settle employee taxes on restricted stock and options				545	284
Unrecognized stock-based compensation expense				$ 1,400
Remaining vesting period unrecognized compensation expense is to be recognized				2 years 1 month 6 days
Restricted Stock \| Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				4 years
Restricted Stock \| Non-Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				2 years
Common stock in lieu of cash \| Non-Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 281	286	254
Two year vesting \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting percentage				50.00%
Four year vesting \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting percentage				50.00%
Accounting Standards Update 2016-09 \| Income Tax Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit for stock compensation in income statement				$ 922
Additional Paid-in Capital
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax benefit from stock compensation					$ 789	$ 217