Earnings Per Share (Details)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Reconciliation of basic to diluted weighted average shares outstanding
Weighted average shares outstanding - basic (in shares)	87,138,000	85,864,000
Dilutive effect of stock options (in shares)	1,485,000	2,377,000
Dilutive effect of restricted stock awards and units (in shares)	203,000	335,000
Weighted average shares outstanding - diluted (in shares)	88,826,000	88,576,000
Stock options
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	594,318	57,804
Restricted Stock Units
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	64,054

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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+ 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