Net Income Per Share (Details) (USD $) In Thousands, except Per Share data	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Net Income Per Share [Abstract]
Net income	$ 15,204	$ 7,604	$ 27,362	$ 13,843
Basic net income per share:
Weighted average common shares outstanding	137,608	130,915	136,954	130,487
Basic net income per share	$ 0.11	$ 0.06	$ 0.20	$ 0.11
Diluted net income per share:
Weighted average common shares outstanding	137,608	130,915	136,954	130,487
Weighted average dilutive common share equivalents	4,464	6,996	4,368	6,985
Weighted average common shares and dilutive common share equivalents	142,072	137,911	141,322	137,472
Diluted net income per share	$ 0.11	$ 0.06	$ 0.19	$ 0.10
Anti-dilutive options and share-based awards not included in the calculation	4	2	4	2

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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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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