Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share [Abstract]
Earnings from continuing operations	$ 11,219	$ 12,280	$ 17,881	$ 15,161
Weighted-average shares outstanding for basic earnings per share (in shares)	63,431	63,333	63,431	63,233
Common equivalent shares:
Effect of stock-based compensation awards (in shares)	962	839	952	822
Weighted-average shares outstanding assuming dilution (in shares)	64,393	64,172	64,383	64,055
Basic earnings per share from continuing operations (in dollars per share)	$ 0.18	$ 0.19	$ 0.28	$ 0.24
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.17	$ 0.19	$ 0.28	$ 0.24
Anti-dilutive securities excluded from computation of earnings per share (in shares)			49	54

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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- Definition

Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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- Definition

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

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- Definition

The amount of net income (loss) derived from continuing operations during 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

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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