Earnings Per Share (Reconciliation Of Denominator For Basic And Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share [Abstract]
Weighted average common shares-basic	66,109,297	65,745,555
Plus incremental shares from: Assumed exercise of options	449,220	367,303
Weighted average common shares-diluted	66,558,517	66,112,858
Earnings per share: Basic	$ 1.32	$ 1.26
Earnings per share: Diluted	$ 1.31	$ 1.25

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References+ Details

- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of call options and warrants using the treasury stock method.

+ References

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-Glossary Treasury Stock Method

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-Glossary Warrant

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

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-Glossary Weighted-Average Number of Common Shares Outstanding

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