Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	68,662	168,362	57,759	293,062
Basic	66,628,747	66,311,958	66,628,027	66,240,225
Plus incremental shares from: Assumed exercise of options	276,807	344,802	275,352	381,295
Weighted average common shares-diluted	66,905,554	66,656,760	66,903,379	66,621,520
Earnings per share: Basic	$ 2.55	$ 1.30	$ 6.57	$ 4.36
Earnings per share: Diluted	$ 2.54	$ 1.30	$ 6.54	$ 4.33

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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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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- 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.

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- 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.

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