Stock-Based Compensation (Details) (1999 Stock Option Plan [Member], USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
1999 Stock Option Plan [Member]
Shares [Roll Forward]
Outstanding, beginning of period (in shares)	77,000
Exercised (in shares)	4,000	4,500
Forfeited or expired (in shares)	0
Outstanding, end of period (in shares)	73,000
Exercisable, end of period (in shares)	73,000
Weighted Average Exercise Price Price Per Share [Roll Forward]
Outstanding, beginning of period (in dollars per share)	$ 22.82
Exercised (in dollars per share)	$ 14.83
Forfeited or expired (in dollars per share)	$ 0
Outstanding, end of period (in dollars per share)	$ 23.26
Exercisable, end of period (in dollars per share)	$ 23.26
Weighted Average Remaining Contractual Term [Abstract]
Outstanding	3 years 11 months 1 day
Exercisable	3 years 11 months 1 day
Aggregate Intrinsic Value [Abstract]
Outstanding	$ 745
Exercisable	745
Intrinsic value of options exercised in period	$ 74	$ 42

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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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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the 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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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including 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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Number of share options (or share units) exercised during the current period.

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