Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Number of Stock Options
Outstanding, beginning of period (in shares)	414,769
Exercised (in shares)	(27,250)
Canceled/Forfeited (in shares)	(1,667)
Outstanding, end of period (in shares)	385,852	414,769
Exercisable (in shares)	333,353
Weighted Average Exercise Price
Outstanding, beginning of period (in USD per share)	$ 19.07
Exercised (in USD per share)	15.93
Canceled/Forfeited (in USD per share)	22.90
Outstanding, end of period (in USD per share)	19.28	$ 19.07
Exercisable (in USD per share)	$ 18.29
Weighted Average Remaining Contractual Life (years)
Outstanding	4 years 4 months 49 days	5 years 29 days
Exercisable	3 years 8 months 79 days
Aggregate Intrinsic Value
Outstanding, beginning of period	$ 1,814
Exercised
Outstanding, end of period	2,370	$ 1,814
Exercisable	$ 2,312

Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]

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Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Remaining Contractual Term [Abstract]

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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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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-Subparagraph (c)(1)(iii)
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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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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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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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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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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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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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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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