Acquisitions (Pro Forma Information Of Acquisition) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Acquisitions [Abstract]
Total revenue	$ 182,276	$ 150,590	$ 527,727	$ 445,550
Net income	$ 47,279	$ 33,409	$ 132,837	$ 99,070
Earnings per share, Basic	$ 0.51	$ 0.37	$ 1.44	$ 1.09
Earnings per share, Diluted	$ 0.50	$ 0.36	$ 1.41	$ 1.06

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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