Acquisitions (Details 2) (D&D Holdings Limited [Member], 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
D&D Holdings Limited [Member]
Business Acquisition, Pro Forma Information [Abstract]
Service revenues	$ 267,552	$ 222,140	$ 777,665	$ 615,217
Net income	$ 17,941	$ 13,036	$ 42,787	$ 24,732
Basic net income per share	$ 0.13	$ 0.10	$ 0.31	$ 0.19
Diluted net income per share	$ 0.12	$ 0.09	$ 0.30	$ 0.18

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.

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