Employee Benefit and Stock Compensation Plans - Summary of Changes in Stock Option Awards (Details)	9 Months Ended
Sep. 30, 2017 $ / shares shares
Employee Benefit and Stock Compensation Plans
Shares, Outstanding - beginning of year \| shares	285,999
Shares, Granted \| shares	34,500
Shares, Exercised \| shares	(96,703)
Shares, Forfeited \| shares	(15,200)
Shares, Outstanding - end of year \| shares	208,596
Shares, Exercisable - end of year \| shares	112,952
Weighted average exercise price, Outstanding - beginning of year	$ 10.45
Weighted average exercise price, Granted	16.94
Weighted average exercise price, Exercised	9.80
Weighted average exercise price, Forfeited	11.99
Weighted average exercise price, Outstanding - end of year	11.71
Weighted average exercise price, Exercisable - end of year	10.10
Weighted average grant date fair value of options granted	$ 3.42

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

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

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