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Stock-Based Compensation (Details Textual) - USD ($) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Oct. 16, 2013 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Stock Based Compensation [Abstract] |  |  |  |
Increase in number of common stock shares authorized | 233,334 |  |  |
Percentage to retain annual restricted stock awards | 50.00% |  |  |
Stock options exercise price description | may not be exercised at a price which is less than 100% of the fair market value of shares at the date of grant. |  |  |
Intrinsic value of stock options exercised |  | $ 664,321 | $ 0 | $ 1,120,153
Proceeds from stock options exercised |  | 354 | 0 | 101,200
Weighted average grant date fair value of restricted stock that vested during |  | 2,300,000 | 2,116,000 | 1,522,000
Net value of unrecognized compensation cost related to unvested restricted stock awards |  | 4,063,000 | 4,223,000 | 3,993,000
Restricted stock [Member] |  |  |  |
Stock Based Compensation [Abstract] |  |  |  |
Stock-Based Compensation expense |  | 2,279,000 | 2,101,000 | 1,655,000
Recognized tax benefits |  | $ 912,000 | $ 840,000 | $ 662,000
Common Class A [Member] | Convert For Class B [Member] |  |  |  |
Stock Based Compensation [Abstract] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 280,000 |  |  |
Common Class A [Member] | Stock Option [Member] |  |  |  |
Stock Based Compensation [Abstract] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 900,000 |  |  |
Common Class A [Member] | Incentive Compensation Plan [Member] |  |  |  |
Stock Based Compensation [Abstract] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 620,000 |  |  |
Common Class B [Member] | Stock Option [Member] |  |  |  |
Stock Based Compensation [Abstract] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 280,000 |  |  |

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- Definition Describes the stock options exercise price. + References No definition available. + Details
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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) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Unrecognized cost of unvested share-based compensation awards. + 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) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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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. + 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 (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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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. + 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 (d)(2) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + 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 (a)(3) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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