Stock-based Compensation Plan (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-based Compensation Plans
Number of stock-based compensation plans	2
Shares available to grant to employees and directors	2,352,608
Restricted Stock
Restricted Stock Awards
Compensation expense related to awards	$ 2,870,000	$ 2,470,000	$ 1,603,000
Income tax benefit related to awards	1,112,000	957,000	622,000
Unrecognized compensation expense	$ 3,174,000
Unrecognized compensation expense, recognized over weighted-average period	1 year 10 months 24 days
Fair value of awards that vested	$ 2,624,000	1,761,000	953,000
Tax benefit of awards that vested	$ 1,053,000	$ 795,000	$ 532,000
Average remaining contractual term on non-vested awards	11 months
Aggregate intrinsic value of non-vested awards	$ 8,070,000

Number of equity-based compensation arrangement plans.

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Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Tax Benefit

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No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
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-Name Accounting Standards Codification
-Topic 718
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-Paragraph 1
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-Paragraph 2
-Subparagraph (h)(1)(i)
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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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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Weighted average remaining contractual term for equity-based awards excluding options, 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 share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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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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- Definition

Intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options.

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