Earnings Per Share Basic and Diluted Earnings Per Share, Shares (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Abstract]
Weighted-average shares for basic EPS (in shares)	84,612,613	82,608,027	81,949,878
Plus incremental shares related to stock options and warrants (in shares)	80,383	212,624	400,102
Weighted-average shares for diluted EPS (in shares)	84,692,996	82,820,651	82,349,980

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of contingently issuable shares. Contingently issuable shares are those shares that are issuable for little or no cash contingent on certain conditions being met.

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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.

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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