Summary of Stock Option Activity (Details) (Stock Options, USD $)	12 Months Ended
Dec. 31, 2014
Stock Options
Changes in shares granted for stock options for the year
Options outstanding, Beginning Balance	58,810
Options, Exercised	(56,360)
Options, forfeited or expired	(1,450)
Options outstanding, Ending Balance	1,000
Options, Exercisable	1,000
Weighted-Average Exercise Price
Options outstanding, Weighted Average Exercise Price, Beginning Balance	$ 15.47
Options, exercised, weighted average exercise price	$ 15.45
Options, forfeited or expired, weighted average exercise price	$ 15.37
Options outstanding, Weighted Average Exercise Price, Ending Balance	$ 16.73
Options exercisable, Weighted Average Exercise Price	$ 16.73

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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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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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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