Loans and the Allowance for Credit Losses - Loans Identified as TDRs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015 Contract	Mar. 31, 2014 Contract
Financing Receivable, Modifications [Line Items]
Number of Modifications	49	7
Pre-Modification Outstanding Recorded Investment	$ 10,724	$ 245
Post-Modification Outstanding Recorded Investment	10,132	239
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	11
Pre-Modification Outstanding Recorded Investment	1,414
Post-Modification Outstanding Recorded Investment	1,056
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	7	1
Pre-Modification Outstanding Recorded Investment	8,568	91
Post-Modification Outstanding Recorded Investment	8,289	90
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	18	1
Pre-Modification Outstanding Recorded Investment	9,982	91
Post-Modification Outstanding Recorded Investment	9,345	90
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	2
Pre-Modification Outstanding Recorded Investment	42
Post-Modification Outstanding Recorded Investment	57
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	7	4
Pre-Modification Outstanding Recorded Investment	424	121
Post-Modification Outstanding Recorded Investment	421	118
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	1
Pre-Modification Outstanding Recorded Investment	7
Post-Modification Outstanding Recorded Investment	6
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	21	2
Pre-Modification Outstanding Recorded Investment	269	33
Post-Modification Outstanding Recorded Investment	$ 303	$ 31

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524

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- Definition

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