Loans - Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Financing Receivable, Modifications [Line Items]
Balance at time of restructuring	$ 1,955
Commercial and Industrial, Other Commercial [Member]
Financing Receivable, Modifications [Line Items]
Balance at time of restructuring	275
Commercial Real Estate, Buildings, Land and Other [Member]
Financing Receivable, Modifications [Line Items]
Balance at time of restructuring	$ 1,680

Amount of investment in financing receivables (before modification) modified by troubled debt restructurings.

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=7512638&loc=SL6953676-111524

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant