Net Income Per Common Share (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net Income Per Common Share
Weighted average shares used for the basic net income per share computation	132,592,939	125,999,323	132,643,698	122,547,027
Incremental shares from share-based compensation	235,601	202,724	141,515	144,391
Adjusted weighted average shares used for diluted net income per share computation	132,828,540	126,202,047	132,785,213	122,691,418
Unvested shares from share-based compensation that were anti-dilutive	16,200	12,600	16,400	12,600

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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-Name Statement of Financial Accounting Standard (FAS)

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+ Details

- 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.

+ References+ Details

- 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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+ Details