Stock-Based Compensation - Stock Option Activity (Details) (USD $)	12 Months Ended
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Expired, weighted-average exercise price per share	$ 15.81
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding - beginning of period (in shares)	797,805
Exercised (in shares)	(286,242)
Expired (in shares)	(39,267)
Forfeited (in shares)	(51,702)
Outstanding - end of period (in shares)	420,594
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding - beginning of period, weighted-average exercise price per share	$ 16.70
Exercised, weighted-average exercise price per share	$ 9.96
Forfeited, weighted-average exercise price per share	$ 8.64
Outstanding - end of period, weighted-average exercise price per share	$ 19.14
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options exercisable - end of period (in shares)	420,594
Options exercisable, weighted-average exercise price per share	$ 19.14
Outstanding, weighted-average remaining contractual life (years)	2 years 6 months 25 days
Options exercisable, weighted-average remaining contractual life (years)	2 years 6 months 25 days
Outstanding, aggregate intrinsic value	$ 552,242
Options exercisable, aggregate intrinsic value	$ 552,242

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

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

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