Acquisition And Disposition Activity (Supplemental Pro Forma Information) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Interest and noninterest income	$ 630,776	$ 568,689
Net income	$ 77,372	$ 54,800
Earnings per share - basic	$ 2.59	$ 1.87
Earnings per share - diluted	$ 2.58	$ 1.86

Pro forma basic earnings per share or earnings per unit, which is commonly presented in initial public offerings based on the terms of the offering.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph b

-Subparagraph 7

-Article 11

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- Definition

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=7659399&loc=d3e1392-128463

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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.

+ References

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- Definition

Pro forma diluted earnings per share, which is commonly presented in initial public offerings.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph b

-Subparagraph 7

-Article 11

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