Mergers and Acquisitions (Pro Forma Information Estimated) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Business Acquisition [Line Items]
Revenue (net interest income and non-interest income)	$ 486,818	$ 445,940
Net income	96,299	66,569
Net income available to common stockholders	$ 94,711	$ 64,981
Earnings per common share - basic	$ 0.69	$ 0.49
Earnings per common share - diluted	$ 0.69	$ 0.49

Business Acquisitions Pro Forma Net Income Loss Attributable To Common Stockholders

No definition available.

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- Definition

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Name Statement of Financial Accounting Standard (FAS)

-Number 141

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

+ References

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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.

+ References

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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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