Stock-Based Compensation (Schedule of Stock Option Activity under the Plans) (Details) (USD $)	6 Months Ended
Jun. 30, 2011
Stock-Based Compensation
Number of Shares, Outstanding at January 1, 2011	1,274,107
Number of Shares, Granted	7,600
Number of Shares, Forfeited/canceled/expired	(38,971)
Number of Shares, Exercised	(125,666)
Number of Shares, Outstanding at June 30, 2011	1,117,070
Weighted-Average Exercise Price, Outstanding at January 1, 2011	$ 11.96
Weighted-Average Exercise Price, Granted	$ 20.73
Weighted-Average Exercise Price, Forfeited/canceled/expired	$ 18.30
Weighted-Average Exercise Price, Exercised	$ 9.33
Weighted-Average Exercise Price, Outstanding at June 30, 2011	$ 12.10

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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

+ References

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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.

+ References

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The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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Net number of share options (or share units) granted during the period.

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- Definition

The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.

+ References

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-Publisher FASB
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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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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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