Stock-based Compensation, Stock Option Awards (Details) - Stock Options [Member] - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Stock-based Compensation [Line Items]
Term of awards	10 years
Options, Outstanding [Roll Forward]
Outstanding at the beginning of the year (in shares)	184,407
Granted (in shares)	10,993
Exercised (in shares)	(21,656)
Forfeited (in shares)	(3,487)
Expired (in shares)	0
Outstanding at end of the period (in shares)	170,257	184,407
Exercisable (in shares)	90,193
Expected to vest, assuming a 0% forfeiture rate over the vesting term (in shares)	80,064
Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding at the beginning of the year (in dollars per share)	$ 14.47
Granted (in dollars per share)	22.31
Exercised (in dollars per share)	10.68
Forfeited (in dollars per share)	17.23
Expired (in dollars per share)	0
Outstanding at end of the period (in dollars per share)	15.40	$ 14.47
Exercisable (in dollars per share)	13.67
Expected to vest, assuming a 0% forfeiture rate over the vesting term (in dollars per share)	$ 17.35
Options, Additional Disclosures [Abstract]
Outstanding, weighted-average remaining contractual term	6 years 8 months 8 days	6 years 11 months 19 days
Exercisable, weighted-average remaining contractual term	5 years 9 months 18 days
Expected to vest, assuming a 0% forfeiture rate over the vesting term, weighted-average remaining contractual term	7 years 8 months 12 days
Outstanding, aggregate intrinsic value	$ 1,545,296	$ 1,490,009
Exercisable, aggregate intrinsic value	974,685
Expected to vest, assuming a 0% forfeiture rate over the vesting term, aggregate intrinsic value	$ 570,610
Forfeiture rate	0.00%
Unrecognized compensation cost	$ 378,000
Weighted-average vesting period	2 years 6 months
Valuation assumptions used in estimating fair value of option awards [Abstract]
Annual dividend yield	1.03%
Expected volatility	25.48%
Risk-free interest rate	1.64%
Expected term	6 years 11 months 1 day
Weighted-average grant date fair value per option granted (in dollars per share)	$ 5.78
2008 Plan [Member]
Stock-based Compensation [Line Items]
Annual vesting	20.00%
Vesting commencement period from grant date	1 year
2013 Plan [Member] \| Minimum [Member]
Stock-based Compensation [Line Items]
Award vesting period	2 years
2013 Plan [Member] \| Maximum [Member]
Stock-based Compensation [Line Items]
Award vesting period	4 years

The estimated measure of the percentage by which shares are expected to be forfeited.

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The number of exercisable share options (expected to vest) that may be converted as of the balance sheet date.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of expected to vest options that are exercisable.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are expected to vest.

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Weighted average remaining contractual term for expected to vest options that are exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The amount of time before the first tranche of the award starts vesting, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Unrecognized cost of unvested options awarded to employees as compensation.

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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 estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

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 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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- Definition

Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Percentage of vesting of share-based compensation awards.

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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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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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