Business Combinations - Results of Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 2014 Acquisitions [Member]	Jun. 30, 2013 2014 Acquisitions [Member]	Jun. 30, 2014 2014 Acquisitions [Member]	Jun. 30, 2013 2014 Acquisitions [Member]	Jun. 30, 2013 2013 Acquisitions [Member]	Jun. 30, 2012 2013 Acquisitions [Member]	Jun. 30, 2013 2013 Acquisitions [Member]	Jun. 30, 2012 2013 Acquisitions [Member]
Business Acquisition, Pro Forma Information [Line Items]
Total revenues					$ 410,801	$ 365,964	$ 812,972	$ 737,673	$ 326,753	$ 292,242	$ 663,460	$ 596,931
Income before income taxes					106,186	99,431	206,102	211,003	86,506	71,528	186,503	154,953
Net income					$ 64,427	$ 59,975	$ 124,753	$ 127,408	$ 52,179	$ 42,700	$ 112,616	$ 92,511
Net income per share:
Basic					$ 0.44	$ 0.42	$ 0.86	$ 0.88	$ 0.36	$ 0.30	$ 0.78	$ 0.65
Diluted					$ 0.44	$ 0.41	$ 0.85	$ 0.87	$ 0.36	$ 0.29	$ 0.77	$ 0.63
Weighted average number of shares outstanding:
Basic	141,250	140,836	141,428	140,816	141,250	140,836	141,428	140,816	140,836	139,086	140,816	139,044
Diluted	143,032	143,021	143,169	142,938	143,032	143,021	143,169	142,938	143,021	141,828	142,938	141,664

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The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect per basic share of common stock for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

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-Name Accounting Standards Codification

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